How can the universe be infinite?

Question: I've heard from renowned astrophysicists that we don't yet know whether or not the Universe is infinite. How is that possible regarding the big bang theory is accepted (as they all do)? Are they referring to the existence of other Universes when they say it could be infinite, or what?
Comment: Please clarify: why do you think that Big Bang theory and an infinite universe are somehow incompatible? Are you imagining that an infinite universe is incapable of expanding, perhaps? Or is it something else?
Comment: What I mean is, even if it is capable of expanding, if everything originated at the big bang how can that space turn to be infinite in a finite time - the age of the universe.
Comment: Comments are not for extended discussion; this conversation has been [moved to chat](http://chat.stackexchange.com/rooms/41169/discussion-on-question-by-harogaston-how-can-the-universe-be-infinite).
Answer:
What I mean is, even if it is capable of expanding, if everything originated at the big bang how can that space turn to be infinite in a finite time - the age of the universe.

In the standard ΛCDM model of the Big Bang, the universe is infinite and has always been such. The Big Bang singularity happened everywhere, in the sense that far back enough in time, the density diverges to infinity at every place.
But this is just a particular model--it assumes that the universe if spatially flat and is globally homogeneous and isotropic. There are extended models in which it is not exactly flat, and so could be finite even if it is still homogeneous and isotropic (if the curvature is even slightly positive). And of course we don't actually know whether it is homogeneous and isotropic at scales much larger than we actually see. Some inflationary models imply that it isn't.

To clarify: the ΛCDM model uses the assumes a spatially flat FLRW solution of general relativity, in which space is the Euclidean $3$-space The Euclidean $3$-space is the only flat homogeneous and isotropic $3$-manifold, so there no way to make it finite without violating at least one of those modeling assumption (e.g., a flat torus could have the same form for the metric, but would not be globally isotropic).
Comment: @harogaston: "expanding space-time" says nothing about either finiteness or infiniteness, but I've edited the answer to point to the specific part of the model that implies the universe is infinite (*if* we take the model more literally than is justifiable, anyway).
Comment: I don't see how this model implies that the universe is infinite. Taken from the wikipedia page you referred to: "The model includes a single originating event, the "Big Bang" [...], which was not an explosion but the abrupt appearance of expanding space-time [...]. This was immediately (within 10−29 seconds) followed by an exponential expansion of space by a scale multiplier of 1027 or more, known as cosmic inflation."
"expanding space-time" doesn't seem infinite to me. I'm not implying you are wrong, but I understand a different thing from that article.
Comment: @Stan when you say that the BB singularity happened everywhere, do you mean that there were an infinite number of BB singularities, one for each point?
Comment: @mick No, because thinking of singularities as necessarily point-like is inappropriate. If you cut a hole in a sheet, it's not useful to think of it as infinitely many holes, especially since there's usually no way to 'fill in' the 'missing piece' anyway. Singularities are even more varied in GTR.
Comment: The age of the universe (or multiverse) is not necessarily finite, although logical considerations require  that any asymptotically-exponential expansion of space (known as inflation) be balanced between opposite directions, to allow it to be eternal to the past as well as to the future, thereby giving it an infinite age. This is described in cosmologies such as Aguirre and Gratton's "Steady state eternal inflation" and Nikodem J. Poplawski's "Cosmology with torsion".  Poplawski has numerous related papers (available free on the Arxiv website), written between 2010 and 2020.
Comment: I have to add that, in his early papers, Poplawski refers to his cosmology as "an alternative to cosmic inflation":  However, it's generally considered to be a version of inflation, differing from the earlier (1980's) version, that was based on a hypothetical scalar field.
Answer: I think the source of confusion between the two concepts - the Big Bang singularity and an infinite universe - is the misconception that the universe began as a finite expanse originally. This misconception easily arises from analogies using present-day logic and numbers that were not applicable in the early universe. For example, I've heard it said that shortly after the Big Bang, the entire observable universe was the size of a grapefruit, but that explanation neglects to mention that grapefruits would have been much larger then.
The problem is that space is where we can measure how large something is, but space expands, so something that is a certain distance away currently was a lot closer a long time ago, even if neither object has moved in the normal sense. As an analogy to help illustrate the effect:
You and I are standing on a preposterously large deflated balloon. You set down a meter stick, make a mark on the balloon at each end and we each stand on one mark and are now a meter apart. Then I turn on a pump and start inflating the balloon. As the balloon inflates, the surface stretches out and you and I appear to get farther from each other, when though we're not 'moving' (e.g. walking away from each other): now we have conflicting sets of information to consider; according to the marks on the balloon surface we're still one meter apart, but according to the meter stick in your hand (which is not expanding) the distance is greater than that.
Note that while I called the balloon "preposterously large," it could have been infinitely large and still behave the same way. I point this out because I've seen in comments on other answers that you don't see how space could be both infinite and expanding - that if it's expanding, then it must have been previously finite. That is incorrect: in fact, because infinity is the quality of unboundedness, something that is infinitely large can always get bigger, because by definition there is no upper bound on its size.
Note also that if you recorded the earlier analogy in reverse, it would appear that space was shrinking such that a several-meters distance between us reduced over time to one meter. If you continue shrinking the universe in such a manner, it eventually becomes the case that there is zero distance between us. And if you apply that to a scenario where there are people infinitely distributed across the balloon, all of them would come closer together as the balloon deflated, until there was zero distance between any two people... in theory, at least, since real human beings have size. Energy and space don't have size, however, so at the point of the Big Bang, space was still infinite (since an infinite/unbounded space cannot shrink to become finite/bounded) but the distance between any two points in space was zero.
So if you could go back in time to the Big Bang you'd see an infinite ocean of energy, since all the energy was "shoulder-to-shoulder" (infinitely dense) but it rapidly expands (and therefore cools) to the point that basic particles can form, then later matter and molecules. Of course since your size would depend on the metric of space, it wouldn't necessarily look like space was expanding, but simply like the energy and matter were cooling down. In fact we still see this as an effect of spatial expansion in the redshift of light from distant sources: the light "cools down" or loses energy along the way because it is stretched out on its journey through space.
Comment: I understand what you mean, but the language is ambiguous - I was thinking that if we had a grapefruit today and wound back time, the grapefruit would shrink. If the Milky Way were 10cm across for example, the grapefruit would be ~$10^{-22}$ cm in size, i.e. much smaller.
Comment: When you write "grapefruits would have been much larger then", did you mean *smaller*?
Comment: @Allure I suppose that's a tricky question on a system where the measuring stick is changing size. Think of it this way: the Milky Way and Andromeda galaxies are each 100k to 200k light-years across and about 2.5M light-years separated; but at some point in the past each galaxy in its entirety was squeezed into a centimeter wide space and they were within centimeters of each other; a 10cm grapefruit then would be a viable cosmic-scale measuring device. Today you'd need a lot more of the small modern grapefruit. The expansion of space is what gave everything room to spread out like it is today.
Comment: @Allure on the other hand, grapefruit aren't currently expanding with the universe because they are bound by various forces. Language is ambiguous, but that's why we have mathematics; I only meant to indicate that 10cm used to go a lot further than it does now.
Answer: It is known that the universe that we can see in our telescopes is less than the total universe. Since we cannot see what is beyond the visual edge, we cannot determine if the universe is infinite or finite.
Comment: Sorry, that doesn't answer my question. Even if we cannot see beyond our observable universe, if everything originated at the big bang how can that space turn to be infinite in a finite time - the age of the universe.
Comment: @harogaston I think this was answered in other answers, but you're right.   Finite space can't become infinite.   For the infinite universe model to work, the big bang itself would have happened across infinite space.    We don't know that to be the case, but it's a popular model among people who study this.
Answer: "How" can the universe be infinite? So I am inferring that there must be a 'procedure' of sorts to make it infinite.
Space can exist by itself without having anything. Vacuum, Intergalactic space, the huge voids seen in the large scale structure maps are examples.
This is means no matter how much the universe expands, space cannot break apart like atoms. One may say it has no elastic modulus. One may use this as a basic premise to explain how there can be an infinite universe.
Alternatively, theories of cosmic topology are in good agreement with the predictions of our universe's matter density being very close to 1 which points to a universe expanding forever. (see http://www.scholarpedia.org/article/Cosmic_Topology#fabre:2013)
It cannot be infinite in a finite time because time is space and time are more or less the same. They are one entity called spacetime.
Answer: It would be cool if Hubble saw a signpost marked: "please do not go beyond this point, this is the edge of the universe." perhaps even a wall or a balustrade.
How can the universe be infinite? infinite size, infinite age, infinitely small quantum constructs? The main problem we have with infinity is that it defies human understanding.
Spherical and circular equations pervade the universe: Stars, CMB, planet and moon orbits, atoms, photons, Pi, they all can use sine-cosine equations. Rotations are infinite. Pi and sine-cosine are infinite.
If the cosmos is made up of infinite maths functions, why would it not be infinite?
How many angles does space have? infinity. how long does a galaxy turn around? eternity. The circles of angular momentum go on ad-eternum. rotations are infinite.
Why would there be a spacial limit to infinitely large or infinitely small space? Because it defies human understanding? that's not a good enough reason.
Everything in the known universe depends on mathematical principles which are infinite, numbers are infinite, angles are infinite, generally sine-cosine, linear, circular and spherical objects have infinite turns.
The mandelbrot set is infinite. It's a much simpler equation than the objects of the universe, and it is infinite. So, i'd encourage you to study the mandelbrot and ask yourself: how can it be infinite? Then you will have some advantage to apply that study to objects of the universe.
There is a curious thing that bridges the infinitely large and small objects in the universe: Black hole singularities are nearly entirely composed of sine-cosine maths descriptions, but they withhold millions of suns of atoms in the space the size a money coin or a CD or a nano-meter, all inside a sine-cosine disk, which is a circular phenomenon weighing billions of stars. If suns can fit into basketballs, and perhaps atoms, how can we judge what is big or small at all? If very big things are reborn to very small, and grow to very big again, it's kind of like the circle of life, and it means that you are the center of the universe, which is a good feeling. Atoms and Stars don't matter compared to you.

How can the universe be infinite?


How to filter TCP packets based on flags using Packet Filter

Question: Well, I didn't know exactly how to ask this question, but I know that you can use the keyword flags to especify which flags you want to filter.
According to the documentation of the Packet filter:

To have PF inspect the TCP flags during evaluation of a rule, the
  flags keyword is used with the following syntax:
flags check/mask flags any
The mask part tells PF to only inspect the specified flags and the
  check part specifies which flag(s) must be "on" in the header for a
  match to occur. Using the any keyword allows any combination of flags
  to be set in the header.
pass in on fxp0 proto tcp from any to any port ssh flags S/SA pass in
  on fxp0 proto tcp from any to any port ssh
As flags S/SA is set by default, the above rules are equivalent, Each
  of these rules passes TCP traffic with the SYN flag set while only
  looking at the SYN and ACK flags. A packet with the SYN and ECE flags
  would match the above rules, while a packet with SYN and ACK or just
  ACK would not.

So, I understood the example and why the packet with the flags S and E can pass (because the E flag is not considered due to the mask SA) and why the packet with only the Ack flag can't pass the firewall.
What I didn't understand is why the packet with the flags S and A can't pass the rule S/SA, if the flag S is "on" in the packet header. Maybe the documentation is ambiguous? Sorry if this is a stupid question or an english misunderstood.
I imagine that it can only pass if it MUST HAS ONLY the flag S. In set arithmetic would be something like this:
flag(s) must be 'on' in the header -> flag(s) pertains to the masked subset [pf doc]
only the flag(s) must be 'on' in the header -> flag(s) is egual to the masked subset [what I understood from the example given]
Thanks in advance!
Answer: This means that you're looking at two flags S & A but you match if and only if S is "on" AND A is "off".
flags S/SA

 ---------------
| S | A | Match |
 ---|---|-------
| 0 | 0 | No    |
| 0 | 1 | No    |
| 1 | 0 | Yes   |
| 1 | 1 | No    |
 ---------------

If you want to match when both SA flags are "on", you'll use flags SA/SA.
flags SA/SA

 ---------------
| S | A | Match |
 ---|---|-------
| 0 | 0 | No    |
| 0 | 1 | No    |
| 1 | 0 | No    |
| 1 | 1 | Yes   |
 ---------------

Comment: I agree with you on that point. As I also use `iptables` on Linux I deducted that the behavior should be similar.
Comment: This is what I was thinking after looking the example @Spack . Don't you agree the documentation is ambiguous? It says that the flag(s) in the check part must be 'on' in the header. So the case you pointed when you have S and A, would also match. It doesn't say that only the flag(s) in the check part must match


Is max-pooling really bad?

Question: Hinton doesn't believe in the pooling operation (video). I also heard that many max-pooling layers have been replaced by convolutional layers in recent years, is that true?
Answer: In addition to JCP's answer I would like to add some more detail. At best, max pooling is a less than optimal method to reduce feature matrix complexity and therefore over/under fitting and improve model generalization(for translation invariant classes).
However as JCP begins to hit on.. there are problems with this method. Hinton perhaps sums the issues in his talk here on what is wrong with CNNs. This also serves as motivation for his novel architecture capsule networks or just capsules.
As he talks about, the main problem is not translational variance per se but rather pose variance. CNNs with max pooling are more than capable of handling simple transformations like flips or rotation without too much trouble. The problem comes with complicated transforms, as features learned about a chair facing forwards, will not be too helpful towards class representation if the real-world examples contain chairs upside down, to the side, etc.
However there is much work being done here, mostly constrained to 2 areas. Those being, novel architectures/methods and inference of the 3d structure from images(via CNN tweaks). This problem was one of the bigger motivators for researchers throughout the decades, even David Marr with his primal sketches.
Answer: Max pooling isn't bad, it just depends of what are you using the convnet for. For example if you are analyzing objects and the position of the object is important you shouldn't use it because the translational variance; if you just need to detect an object, it could help reducing the size of the matrix you are passing to the next convolutional layer. So it's up to the application you are going to use your CNN.

Is max-pooling really bad?


Nikon AF-S Nikkor 70-300mm 1:4.5-5.6 G ED Lens will not autofocus

Question: I have a Nikon AF-S Nikkor 70-300mm 1:4.5-5.6 G ED Lens that I purchased in Feb of 2013.  I have been using this lens with my Nikon D3200.  Up until this point my lens and camera have been completely fine.  However, my autofocus suddenly stopped working.  I know it is not my camera as my autofocus works with every other lens I own.  I keep my lens all very clean, I tried resetting all my options to factory resets, the lens has never taken a hard fall, and yes it is set on M/A.  When I try to autofocus I can hear my camera trying to focus, but nothing happens.  What is the problem and how can I fix this? I really need this lens!
Comment: Similar to this previous question, [How can I fix a broken lens/autofocus?](http://photo.stackexchange.com/questions/4518/how-can-i-fix-a-broken-lens-autofocus), I would simply recommend sending your lens to a Nikon authorized repair shop and get a quote for repairing it.
Answer:
When I try to autofocus I can hear my camera trying to focus, but nothing happens.

You should not be able to hear your camera focus because your camera doesn't have a built-in focus motor. Therefore, you are hearing the lens focus (or at least the motor inside).
So, you can hear the motor in the lens but the lens elements don't move so you get focus. I would from this assume that there is a mechanical defect in the lens.

The above only holds, if you are actually hearing noises caused by focusing. Other reasons I could think of are that the M/A switch is in the right position but not working. Try toggling it a few times.

What you also could be hearing is image stabilisation (IS)! On my copy of that lens, this is much louder than focusing.
If it is indeed IS that you are hearing, then all options for what is wrong are on the table, again.


How to explain a war scene?

Question: In my novel, I have a part where there is a war scene, and I need to explain it precisely from the king's point of view. How can I explain the war graphics vividly?
Answer: For starters, avoid getting into details.
This is true generally, and even more so during battle. People are moving quickly! It is no time for details.
I've read a battle-scene where the author described specific attacks, and the impression I had was that the fighting was happening in slow motion. With classical music in the background. Really slow music.
The best battle-scene I remember reading included almost no descriptions of the actual battle, but of colors, emotions and cries. Needless to say, this scene left a powerful impression, and I actually felt like I was there.
Of course, since you're writing this from the king's perspective - and the king is normally in the back lines - you'll have to get into overall detail of what's happening on the field. After all, the king needs to know what's going on!
See also: Good action scenes
Comment: Thank you. It's very helpful. In the scene, the king itself is on the battle ground and is fighting along with his men for he has a small army, and the opponent is very strong. He will see his men dying. I will use your suggestion and use less descriptions about it. But the feeling I need to portray here is that they are happy and proud to die for the prosperous kingdom and generous king. And I will explain the blow on the king extendly to bring out the actual affect of the war. I would appreciate any suggestions on it.
Comment: @JATagala, you can have one of the men sacrifice himself to save the king. This would show their devotion to the cause, especially if the dying soldier had plans for the future or a family. Exactly what do you mean when you write "the blow on the king"? Do you mean  the way he is affected by seeing his men die?
Comment: With "the blow on the king" I mean, the king will die too along with his men on the battle field. When they would head for the war, they all will be aware that there is no return. Before the war, the king will ask his men, "Once we go out on the battle field, there will be no return, so stay only those who want to die along with me."
All his men will stay back.
Answer: I'm just an amateur writer, but a seasoned soldier.  If I were to write a combat or battle scene, I think I would probably try to describe the calamity of battle.
Confusion sets in very quickly when you lose the initiative in a fight.  At that point, there is a good deal of sensory overload.  Training kicks in and fighting become an instinctive struggle for pure survival.  Extremely seasoned warriors can delay this outcome for longer than a 'greener' force.
So, if you have a well-trained military, with several campaign ribbons on its battle-standard, you might consider a very lucid and methodical description of the general mechanics of the fight.  Leave details to the imagination, except where they serve the plot.
If your force is inexperienced, I would use the opportunity to capture as many non-combat related details as possible during the fight, to heighten the reader's feeling of confusion in the fog of war.
Answer: How do you explain anything vividly? Observe with all your senses, and add emotions and thoughts. Do the research.
I will express hope that you have not personally been in a war scene, so you would have to find some other way of observing, or use your imagination. You could watch combat footage or news reports of war, you could interview veterans, you could read war memoirs, or you could read other fictional books with war scenes.
Then don't just describe the parry-thrust-advance of swordwork, but how it feels to swing the sword — how it hits his opponent, the shock that comes back up the king's arm (or doesn't), the smell of perforated bowels, the smears of blood and brains, the terrible screaming of dying men. Maybe find some Society for Creative Anachronisms chapter and talk to the folks there about how sword-fighting works. (Substitute whatever weaponry or tech is appropriate for your setting, of course.)
Answer: Gritty details go a long way, so I would recommend not dwelling on them too much. I feel like it would be more realistic for someone in a battle to be focused on fighting and staying alive, rather than witnessing all the atrocities happening around him.
There's an old adage along the lines of "after the first shot is fired, all battle plans go out the window." If your king is in charge of this battle, at least in some capacity, it would be good to focus on how easily everything breaks down into chaos, both in a specific battle, and in troop positioning/tactics. For example:

Poor troop morale

breaking formation
running
abandoning
becoming obstinate

Plans:

backfire
fail
partially succeed
succeed with undesired results
are not accurately communicated

Unknown, enemy plans/sabotage attempts:

succeed
partially succeed
fail but with undesired results

Equipment:

malfunctions
is inappropriately apportioned (like wool uniforms being used in Africa)

Supply lines:

are severed
get waylaid

Sneaky tactics:

night fighting
"pretending" to run, only to achieve advantageous ground
guerrilla warfare

Communication breakdown

pre-radio, commanders had to shout orders or have instruments announce them
missives / carrier pigeons not arriving

Etc, etc.
Some books that hit these realistic difficulties of war as well as the gritty violence are Black Hawk Down and Red Badge of Courage. Even if they aren't your specific time period, the concepts can be easily adopted.

How to explain a war scene?


How do youtube professionals record audio for their video?

Question: If some professional has a video, and they want to do a voiceover for it, how do they do it?
Do they first remove unwanted clips from video and then record audio using audacity while seeing the video as it is running?
Answer: If you are referring to tutorials or commentary then yes, you would record the original performance (perhaps with computer sound), while thinking of your audience. When I record tutorials for software, I often perform the example while talking, then go back and edit it down to a reasonable length. I remove unwanted sound, then re-voice the finished edit from a script (doesn't have to be fully written, can be bullet points).
This way I can make mistakes in delivery and restart as many times as I like.
Then i lay that recording back over the edited pictures. At this point I may find that I need to make the video longer to accommodate the new voice over. So there is a little bit of give and take. It is quite hard to manage picture lock without sound.
Answer: The process you are describing is called ADR (automated dialog replacement) or dubbing - after picture is locked, lines are recorded separately in a controlled environment and mixed to match the appropriate sonic perspective the required. If you were to adr all of the lines in a vid, you would also then add in a room tone/ambience to give it a soundbed to live in. If you are replacing a few lines that cannot be salvaged, you would then mix in to match the remaining lines and mix the adr'd lines within the ambience of that scene. Most hollywood and large productions are 75-85% ADR - shooting conditions/locations or props etc create a ton of sonic pollution, so most on location sound recordists do their best to capture what will be the reference track once the project goes to post production.
There are a few common recording techniques - productions that go through the trouble of ADR are usually a higher production value than Audacity, most likely using ProTools or other industry standard DAWs.
The two basic ways to record ADR would be to loop the video/original lines to be replaced in your recording program, so the talent can watch and deliver multiple takes to match the on screen performance. Another method, is to have the talent parrot their performance; you start recording, the actor hears the performance, and then just mimmics right after. I find the second easier because youre not asking someone to anticipate the video they want to match, they can just focus on trying to mimmic their own earlier performance - let the recording engineer focus on if the audio syncs with picture, let the actor focus on delivery.


Problems with software installation after kernel update

Question: I am using Ubuntu 13.04 64 bit.
I decided to install Linux kernel 3.10 which was released recently so, i downloaded the kernel and header packages from kernel.ubuntu.com since it's not in raring repositories. I was able to install Headers without problems but when i tried to install the kernel, i got this error
root@pulkit-Vostro-1014:/home/pulkit/Downloads# dpkg -i kernel.deb
(Reading database ... 222087 files and directories currently installed.)
Preparing to replace linux-image-3.10.0-031000-generic 3.10.0-031000.201306301935         (using kernel.deb) ...
Use of uninitialized value in concatenation (.) or string at   /usr/share/perl5/Debconf/DbDriver/File.pm line 44, <DEBCONF_CONFIG> chunk 3.
Use of uninitialized value in -e at /usr/share/perl5/Debconf/DbDriver/File.pm line 46, <DEBCONF_CONFIG> chunk 3.
Use of uninitialized value in pattern match (m//) at /usr/share/perl5/Debconf/DbDriver/File.pm line 47, <DEBCONF_CONFIG> chunk 3.
Use of uninitialized value $directory in -d at /usr/share/perl5/Debconf/DbDriver/File.pm line 48, <DEBCONF_CONFIG> chunk 3.
Use of uninitialized value $directory in concatenation (.) or string at /usr/share/perl5/Debconf/DbDriver/File.pm line 49, <DEBCONF_CONFIG> chunk 3.
debconf: DbDriver "config": mkdir :No such file or directory
dpkg: error processing kernel.deb (--install):
subprocess new pre-installation script returned error exit status 1
Examining /etc/kernel/postrm.d .
run-parts: executing /etc/kernel/postrm.d/initramfs-tools 3.10.0-031000-generic   /boot/vmlinuz-3.10.0-031000-generic
run-parts: executing /etc/kernel/postrm.d/zz-extlinux 3.10.0-031000-generic   /boot/vmlinuz-3.10.0-031000-generic
P: Checking for EXTLINUX directory... found.
P: Writing config for /boot/vmlinuz-3.9.7-030907-generic...
P: Writing config for /boot/vmlinuz-3.8.0-25-generic...
P: Writing config for /boot/vmlinuz-3.10.0-031000-generic...
P: Writing config for Windows 7 (loader) on /dev/sda1...
P: Installing debian theme...cp: cannot stat '/usr/share/syslinux/themes/debian-   wheezy/extlinux/memtest.bin': No such file or directory
run-parts: /etc/kernel/postrm.d/zz-extlinux exited with return code 1
Failed to process /etc/kernel/postrm.d at /var/lib/dpkg/tmp.ci/postrm line 328.
dpkg: error while cleaning up:
subprocess new post-removal script returned error exit status 1
Errors were encountered while processing:
kernel.deb

Also, whenever I try to install/remove any software I get this:
root@pulkit-Vostro-1014:/home/pulkit/Downloads# sudo apt-get install vlc
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: The package linux-image-3.10.0-031000-generic needs to be reinstalled, but I can't     find an archive for it.

Please help me out!
Comment: Try `sudo apt-get clean && sudo apt-get remove linux-image-3.10.0-031000-generic`. If that does not work try `sudo apt-get -f install`.
Answer: P: Installing debian theme...cp: cannot stat '/usr/share/syslinux/themes/debian-wheezy/extlinux/memtest.bin': No such file or directory

I countered this with the bold:
touch /usr/share/syslinux/themes/debian-wheezy/extlinux/memtest.bin

Use at your own risk, but it worked for me.
ps: I didn't try booting into memtest


What is the difference between a nation and a state?

Question: These terms seem to be used interchangably - what is the difference between them?
Additionally, why is it that a "state" appears to be just an entity of a federal government in certain contexts - e.g., "the United States?"
Comment: Related English Language Learners question: [*When to use words "country" and "state" while describing a sovereign political entity?*](http://ell.stackexchange.com/q/392/191)
Answer: There are three different things to define here:

State: "A state is an organized community living under a unified political system, the government" (Wiki definition).
This is basically just a community (usually in a specified territory) that was ruled by a specific government.
It may or may not have been sovereign.
Nation: A nation may refer to a community of people who share a common language, culture, ethnicity, descent, or history (Wiki).
Note that a nation has no required geographical tie-in (as an extreme example, consider the nation of Roma, or post-Diaspora-pre-modern-Israel Jews). But they must/should, as a rule, share history, culture and language (never thought I'd quote Stalin on a Politics.SE :)
The idea of a nation and a state being the same thing ("Nation-state") is fairly new in modern politics[1] (it came about as one of the consequences/results of Peace of Westphalia, which ended the 30-year-war in Europe, when the concept of "Westphalian sovereignty" was introduced).
Before that, a vast majority of people did not - per se - had a firm notion of a "nation", at least in Europe. Your loyalties were either to your immediate locale (village, town, clan), or to your hierarchical ruler (feudal lord, usually, and ultimately whichever prince/Emperor ruled the whole territory of the state).
But you didn't consider the territory ruled by that Emperor to be "your" state - the fact that they shared the ultimate liege lord was irrelevant both practically, AND philosophically/culturally.

Also, as alluded to by @Affable's answer, most of the states through history did NOT match the notional nations geographically, and many crystallized as nations much later than 1648. For example, Russia at first had a gazillion city-centered small states. Then, when they were unified under a central government, they fairly promptly ate up the territories of OTHER nations and turned into transnational empire, which they still in effect are. Germany wasn't really unified as a nation till either  Congress of Vienna in 1815 or even Bismarckian unification in mid-19th century. Italy was a collection of warring states till 1861 or so. Islamic empires/khaliphates were transnational and Arab Nationalism didn't really exist till 20th century, after Ottoman Empire was gone.

[1] - There were earlier attempts and ideas to create a nation-state - for example, I would consider Alexander the Great's efforts to be such, since he tried to unify the culture of his empire (and definitely succeeded doing so in the scope of Greek Peninsula itself). I'm not sure how to classify Rome - they tried to also strongly unify the culture of their empire, and had a Latin as common language.
Comment: @JMBecker while Rome was multi-cultural, there were common constructs present throughout the empire (e.g. aqueducts, highways, amphitheaters) which were markers of Roman culture and engineering.
Comment: Rome was an empire, which by necessity must be both multi-national and multi-cultural... It can even include "nominally" sovereign states, however the economic system is always one.
Answer: In the age of Empire, these were totally different things.  A nation was an ethnological term - it referred to a people group.  A state, on the other hand, was a governmental authority.
As such, the Austro-Hungarian Empire would have been a single state with mutiple nations - including Austrians, Magyars (Hungarians), Gypsies, and others.
With the breakup of Empires generally, however, the goal came to be that each people group (nation) would have its own state - the nation-state - in which it could pursue its own identity.
Answer: These terms seem to be used interchangably - by whom and where? These are complete different things.
The nation - is the sociological phenomenon - the community of people with awareness of common origin, history, language and culture. The religion can also be the unifying factor - like with the Jewish nation before the creation of Israel.
The state - is the legal term of the administrative structure having the power over the given territory.
The state is the territorial entity, the nation - the sociological. The nation can exist without any state; it can be scattered over the whole world and still be the nation. The state can exist without any nation, by ruling over various nations having nothing in common; an example is an empire.
Comment: "State" is also a sociological construct, which differs strongly from the state as an administrative structure.
Answer: Nation is a way of feeling,thinking and living,it is a psychological condition of the mind which emphasizes the consciousness of unity due to spiritual or other feelings.
The state emphasizes political unity and objectivity which is a condition of law,the state is an enforceable obligatory condition inseparable from all civilized ways of living
Answer: A state may be defined as a politically organised body of people inhabiting a defined geographical entity with an organised legitimate government whilst a nation is a group of people with a common race,culture,religion and historical experiences but who may not necessarilly live together in a single territory.
Answer: The state is a concrete political organisation where as the nation is abstract and spiritual.The state can exist in the absence of national consciousness,whereas a nation cannot.
Answer: The state is a political community living in a given territory with sovereignty.The nation is a social and psychological community based on identical feeling of common culture and heritage. The term nation-state can be traced in the writings of Machiavelli in the beginning of modern age with the union of fragmented Italy. Maleque
Comment: Do you have specific Machiavelli cites? That would improve the question. Also, as per "About" pages, signatures in posts are strongly discouraged.
Answer: The following defines all 3 terms. To ease reading, I do not use blockquotes, but everything below the line below are verbatim quotations.
Source:  Introduction to Politics: First Canadian Edition (2012 1 ed.) by Garner, Ferdinand, et al.

[p 281:]
We should also give the terms state and nation some scrutiny. Although they are often used synonymously (or joined together to produce "nation-state"), they actually refer to two quite distinct entities. For our purposes—and those of politics more generally—we
[p 282:]
might define the "state as a distinctive political community with its own set of rules and practices, more or less separate from other communities. For the specific purposes of IR [International Relations], "the state" refers to the modern sovereign state, which possess a "legal personality" and is recognized as possessing certain rights and duties. […]
We now turn to the idea of the nation, a term that refers specifically to "a people" as opposed to a formal entity. There is no widely agreed definition of what constitutes "a people"; in general, though, the term generally denote[s] a kind of collective identity that is grounded in a shared history and culture and may or may not lay claim to some kind of political recognition as well as a specific territory. […]
[p 283:]
[...] These examples reflect the commonly accepted conflation of state and people that produces the familiar term "nation-state," which, again, reflects the principle of national self-determination. In principle, though, the matching of state and nation has rarely, if ever, been so neat and unproblematic. There is virtually no state in the world that contains a single, homogeneous nation. Many states  are made up of two or more "nations" and even these are not always distinct.  [...]
Answer: The definitions of "nation" you have been given, are not correct.
It is important to note that nations did not exist before the 19th
century. It wouldn't have crossed anyone's mind that they belonged to
a specific nation. Ethnic groups certainly did exist, as did tribes and
clans, but nations did not.
During the 18th century, philosophers began thinking about human
rights. It was no longer a given that serfs should unquestionably obey
their masters and that the kings powers were provided to them by
God. People began to think that they were more equal than previously
thought.
This advancement lead to new societal structures and revolutions. The
kings lost their power to rule and were replaced by states. The idea
that granted states authority to rule, were Nationalism; the idea
that people should be divided into nations.
People in a nation should, ideally, feel "togetherness." This
togetherness consists of having common history, race, language,
culture and religion. People must also "feel" as a nation, otherwise
they are "just" a people and not a nation. A people that becomes a
nation experiences a national awakening.
For example, the Nordic countries are among the oldest countries in
the world. But it wasn't until the 19th century that they become
nations. During this period the "identities" of the Swedish and the
Danish nation (and later on also the Norweigan and Finnish) were being
hashed out. Writers began to ponder questions like "What does it mean
to be Swedish?"
In this way, nations were constructed. For some nations, like the
Swedish and the Danish, the existing states matched the new
nations. For other nations, such as the Italian, Jewish, Turkish and
German ones, the states didn't even exist so wars had to be fought to
create them.
Nowadays, the idea of the nation is so ingrained in our minds that we
rarely even think about it. That ones "national identity" is at most
200-300 years old is unknown to most.
Answer: A state is the group of people living in a geographical area with government covered like an  umbrella.where as Nation is the traditional genealogy and who believe that,they have common culture,decent and language living under the state.


How does one official know that a foreign country representative is the proper person to discuss some matters?

Question: The Romanian Prime Minister's visit to Israel triggered a serious political crisis in Romanian political life:

Romania's president has slammed the country's prime minister for
  embarking on a visit to Israel without his authorization.
In Romania's division of power, it's the president who is in charge of
  foreign visits and any foreign trips by the premier have to be
  authorized by the president.
The latest spat comes just a week after Iohannis said Dancila had
  overstepped the mark in saying Bucharest was ready to follow the U.S.
  and move the country's embassy in Israel to Jerusalem from Tel Aviv.

The crisis became so acute that the President asked the Prime Minister to resign.
I am interested in the perspective of the Israeli President, namely how could he know that he was meeting with a person who was not entitled to discuss such matters? Are these things checked before a high level meeting takes place?
Question: How does one official know that a foreign country representative is the proper person to discuss some matters?
Comment: That's what diplomats are for.
Answer: One of the roles of a diplomat is to be an expert on the country to which they are sent.
It would be the job of the diplomats to advise the Israeli Prime Minister if there were any topics that should not be discussed, as they were ultra vires of the Romanian PM.
The extent to which this was done by Israeli diplomats prior to the Romanian PM's visit is unknowable.


Will I see a significant improvement from upgrading from Canon EOS 350D to 550D?

Question: I am an enthusiastic amateur photographer and have a Canon 350 D that I bought about 5 years back. I use this with a Tamron 17-50 2.8 lens, a Canon 50 mm 1.8 mm lens and a Canon 70-200 f 4.0 L lens (with a Canon 1.4 X extender). I like to do some bird photography and also landscapes. I am wondering if my camera body is dated now and if that is the limiting factor for the quality of images that I get from my telephoto L lens. How much improvement in image quality can I expect if I upgrade to EOS 550 D (which I can afford now)? Will the newer sensor and larger number of pixels translate into a noticeable improvement in image quality?
Comment: Is there anything specific about your images that you would like to improve? (inspired by @Nir's answer)
Answer: The difference can be huge or unnoticeable depending on how you use the camera - for example, the faster burst rate means nothing if you never use burst mode or can make a huge difference if you always shoot in burst mode - also better low light performance means nothing if you always shoot in bright sunlight.
You shouldn't be asking if the camera body is a limiting factor - you should be asking yourself what it is you don't like about your photos and then ask here how to fix the problem (and most likely the way to fix the specific problem does not require a new camera body).
But buying equipment is fun, you can always use the specs to rationalize buying a new body  - just think of that wonderful full HD video of birds in flight you can make with the 550D (Important note: I believe shooting video of birds in flight with a DSLR is insanely difficult)
BTW: I have the 550D and I love it, I use it mostly indoors at higher ISO than people here are usually comfortable with and it produces great pictures.
Answer: Snapsort shows a clear comparison of the tech specs of both cameras. To highlight a few of the advantages of the 550D over your 350D (in no particular order):

Capture around 2.5x more detail in your photos.
Maximum light sensitivity is 2 f-stops better.
More than 9x higher resolution screen.
10% better image quality.
0.7 f-stops more dynamic range.
More than 30% faster continuous shooting.
Distinguishes more than 20% more colors.

The main benefit seems to be the higher resolution that will allow you more room to crop photos of birds.
A slightly faster burst rate,  hi-res screen, better low light performance and video capabilities are additional benefits.
Comment: Thanks, Abhimanyu. What I really want is how much real life difference all these technical differences work out to - a somewhat subjective opinion. Does sound like there will be a substantial difference based on your answer. I think the better LCD allowing better immediate review and the higher resolution which will help with crops will make a big difference.
Comment: In terms of making the best out of your L series glass, you can see this link on [DxOMark](http://www.dxomark.com/index.php/en.../Lenses/Compare-Camera-Lenses/Compare-lenses/(lens1)/255/(brand)/Canon/(camera1)/183/(lens2)/255/(brand2)/Canon/(camera2)/619) that compares how your 70-200 lens performs on the different bodies.
Answer: For what it's worth, I too have a 350D.  It's a great camera.
Oddly - even though many newer, better cameras have come out since I first received it back in 2006 - my 350D hasn't started taking worse pictures over the years.  I'm not sure why that is - it surely couldn't be that the marketing for all the new cameras is misleading??
My other camera is a 5DmkII, but I still love the images I get with my 350D.
I only got the 5D because I specifically wanted a full-frame sensor.
My advice: only upgrade if you have a specific need.


I've read that black locust is poisonous to sheep, so will installing black locust poles poison sheep also?

Question: I'm looking at putting black locust posts around my field, but I've read that black locust is poisonous to sheep, but they're excellent fencing poles as they last forever and need no treatment with chemicals. Will the sheep eat the black locust poles if they can?
Comment: All I know is that black locust poles have been used in fences and corrals for centuries. I've never heard of anyone having a problem with sheep nibbling on them. One would presume that this was done without incident or the practice would have been halted long ago.
Comment: Why is this relevant? When in doubt, can't you just use any other type of fencing poles?
Comment: black locust isn't treated with chemicals, and lasts forever.
Comment: I think this is a good question. The question is whether sheep will chew at fence posts, and if they do, whether small quantities of dried black locust are still detrimental to the health of the sheep.
Comment: Trim off the frayed wood after the post is inserted.  Slope the top to the outside of the corral so that leachate isn't on nibbleable grass. I would suggest doing reserch on how poisonous it is, and whether sheep eat it willingly when there is other fodder available.  E.g. Cows find locoweed quite palatable.  They still go crazy.  Cows will not choose to eat water hemlock, but will grab the odd mouthful when eating grass around it.  For a cow the lethal dose is on the order of a kilogram.  Pincherry and has a precursor to cyanide in the leaves.  The deer will nibble, but not enough to kill.
Comment: @acoder From your link: "The black locust tree contains several toxic compounds found in the sprouts, leaves, bark, flowers, and seed pods including a glycoside (robitin) and phytotoxins (robin and phasin)." The black locust wood isn't mentioned here, but I guess you are worried about the bark?
Comment: I'm worried about the bark, and wood once it becomes a pole for pounding.
Answer: Pretty much everything is toxic if you have too much of it.  Water, for example, can be toxic to humans.  The trick to not going insane in this world is to stop looking at lists on websites that claim things are toxic and just approach the issue with logic and caution instead.
If there is no grass in your paddock, your sheep are starving, and you put up a new fence made from freshly-cut locust, then sure, the sheep will rush the fence and eat what they can as fast as they can because it's new and different and they want to get in before the other sheep eat it all.  A few hours later they may get sick and a few days later some may die.  The problem is not the species of tree you are using — it's the fact you're starving your animals and you introduced a large amount of alternative 'feed' quite suddenly.

Note:  For the purpose of this answer, anything that livestock can physically eat is considered to be 'feed' — not just the stuff that you buy in a sack that comes with a nutrition label.  Sheep can't read labels, so the only way for them to find out if something is food or not is to chew on it, eat it, and see if it makes them sick. So grain is feed, hay is feed, fence posts are feed, tool handles are feed, tyres are feed, baling twine is feed, pallets are feed, barn doors are feed...

Sheep (pretty much all livestock) will preferentially eat the feed that tastes the best first.  Then they'll eat the feed that tastes ok.  They'll avoid eating bad-tasting feed until they get hungry.  They'll avoid eating 'toxic' feed — that they think will make them sick — until they are starving.
Introduce new feed in a small, controlled amount.  Let them taste it.  Let them see if they end up with undesirable side-effects.  If nothing bad happens, expose them to a slightly larger amount of the feed a few (three or more) days later.  Observe.  Monitor.  Repeat.
This approach will prevent animals from getting a "massive dose" from the initial — curiosity-driven — exposure.  It will also give them a chance to assess the feed's palatability and to decide how hungry they need to be before they resort to eating it.  When they see it coming back again and again, the novelty factor will wear off.  If the feed isn't palatable then they'll ignore it and go back to eating what they did before — unless you starve them.
You can add blocks of pure arsenic in the middle of your field quite safely if you do it this way.  It's not the feed — it's how you introduce it that determines what the outcome will be.

Day 1 — Put a piece of locust firewood, or about a foot worth of
post, into their field in an 'obvious place'.  Observe.  Monitor.
Day 4 — If they've just nibbed at the wood, you haven't spotted any
strange-coloured faeces, and none are exhibiting any unusual
behaviours, add a second, and perhaps third piece of wood to the
pile.  Observe.  Monitor.
Day 7 — If all seems normal, lean a full post up against some part of
the fence.  Observe.  Monitor.
Day 10 — If all seems normal, lean two or three more posts against
the fence.  Observe.  Monitor.
Day 14 — If all seems normal, lean half-a-dozen more posts against
the fence.  Observe.  Monitor.
Day 21 — If all seems normal, fence in a new paddock entirely with
locust.  Make sure they have plenty of regular feed (i.e. lots of
good grass, maybe some supplementary feed as well) and water — lots
of feed options that you know they like more than the fence posts.
Move the sheep in.  Observe.  Monitor.
Day 30 — Build a campfire and burn the printout from the website that
claims that black locust is poisonous to sheep.

In nature, wild animals are free to pick and choose what they will eat.  Accumulated wisdom (from the herd and the individual) means they don't eat things in quantities that are toxic to them.  When you farm animals in a cage or a paddock, you are 100% responsible for the diet of your livestock.  If you intend to change their dietary options you need to give your animals the opportunity to develop/update their dietary wisdom.  If you don't, and your animals suffer and die, then it's not a random plant's fault — it's yours.
The only thing toxic to farm animals are bad farmers.
PS:

Black locust fence posts will last longer if you strip off the bark.
In wet and clayey soil, giving the part of the post that goes into the ground (plus about 10cm that sticks out of the ground) a sealing coat is advisable.
In sandy and free-draining soil, a band of sealant +/-10cm around the ground contact line is all that is advisable.
A cap on the top will stop water from being drawn down into a post and further extend its life.
If you debark the posts they'll be really, really hard to staple three months later.  You're better off pre-drilling holes for the staples in the comfort of your shed if you leave them that long.
Black locust posts that have been debarked and left out in the elements for three months are so hard that animals would have a hard time eating them even if they wanted to.  No need to worry about anything beyond this point.
Comment: I have no experience with sheep, but any dog I've ever known will ALWAYS keep eating tasty things that make them sick. I will spare the details here. Are sheep/livestock smarter than dogs in this regard?
Comment: LShaver, flock/herd animals accumulate dietary wisdom collectively, and when you breed them the mothers pass the wisdom down to the offspring.  I'm sure that wolves and other multi-generational canine packs would do the same thing.  The poor pooch that you buy from a pet store or rescue hasn't had the opportunity to benefit from this, and since it's probably desexed, any wisdom it accumulates will die with it.  That would logically lead to serial solitary dogs making the same mistake over and over again.  Wisdom isn't the same as intelligence.  My dogs are smart, but my flocks are wise.
Comment: None of the dogs I've owned have kept eating things that make them sick.  One particularly thick mongrel took about three poisonings to realise that snail pellets were not food.  A strategy I've heard of, but not needed to use, is to overdose them.  If your dog ends up sick, and you know what caused it, when they are throwing up, not eating, and otherwise feeling miserable, put *more* of the offending 'food' in the kennel with them.  Supposedly they then associate the smell of the food with being sick and stop eating it.  Putting it in a basket would stop them from eating all of it.


Deleted myself from Facebook group and cannot regain access

Question: I created a closed group and was the sole administrator. Somehow I deleted myself from the group and cannot regain access because I am the person that admits people to the group. What can I do to resolve this issue without having to delete the group? There are so many members, I won't be able to re invite them.
Answer: Per the Facebook FAQ - How can I become a group admin?

You're automatically an admin if you create a group. Otherwise, if you join a group that already has one or more admins, you can ask any of the existing admins to add you as an admin. If you're a member of a group with no admins, you can become an admin by clicking Make Me Admin under Members in the right column.

However, it appears that Facebook needs to update this FAQ, since there's no longer a right column with a Members sections.  Instead, the Make Me Admin option is now under the settings icon (looks like a gear) at the top right of the group page.
So, you will need to privately contact one of your group members and ask him/her to become an admin using the instructions above.  He or she will then be able to add you to the group and make you an admin again.

How do I add more admins to my group?

Click on the About tab
Find a member by scrolling through the page or entering a name in the search box
Click Make Admin under the name of the member you wish to add as an admin
Answer: I'm not sure how Facebook behaves when the admin leaves a group, but its possible that it may assign admin to another user (maybe who ever joined 2nd). If you know anyone who is a member of the group in real life then I'd ask them if they can see who is admin.
Otherwise you can report a problem with groups here by following the Tell us More link at the bottom of this page: https://www.facebook.com/help/issues/groups
Answer: If you delete yourself, or something happens to your account, you remain as a "ghost" admin; meaning the group will still show 1 admin under the member's list, however, no names will be listed.  This prevents an active group from being immediately deleted, however, I've yet to find a way to regain or reconnect as the admin.
Answer: I think that when you delete yourself, it deletes the group if you made the group and were the only administrator.


How to find the loudest part of a mix?

Question: What are fastest methods to find the loudest part of the track during mixing?
Comment: By "loudest part" do you mean the section (e.g. the loud part is at 1 minute 11 seconds into the mix) or the track (e.g. the drums are the loudest)? And by "loud" to you mean subjectively (it sounds the loudest) or physically (delivers the most acoustic energy)?
Answer: Turn your monitor level all the way down until you can't hear anything. Slowly turn it up. The first thing you hear as you turn up the monitors is the loudest thing in the mix.
Comment: The studio i worked at had some very low end speakers (i think they were pulled from old two track machines) and a few engineers i worked with would occasionally listen to one on very low levels to see if anything was really poking out. if all you hear is the snare, good chance your snare is too loud.
Comment: This assumes that the frequency response of your amp, speakers, listening environment and ears remains the same at different volumes. But afaik that's not the case; there's even a button on many home audio systems (usually labelled "loudness") to combat the change in frequency response at low volumes.

How to find the loudest part of a mix?


Override the source of a template field

Question: If I have a template that is inheriting a field from a base template, Is there any way to override the source of that field?
Answer: Branching off of @SzymonKuzniak's answer, the simple answer is "no" but the complex answer is "yes, with some trickery, by tapping into the getLookupSourceItems pipeline."
In order to minimize development cost and maximize your extensibility, maintainability, and reusability, my recommendation would be to write a processor for the getLookupSourceItems pipeline that executes "Source Query" (the name I would give to the Rule Context Folder) rules.
Benefits:

You can create macros for common query patterns (e.g. Site Home, Site Globals, etc.)
You can create far more powerful filters than those provided OOTB
You can use conditions to make the rules template specific, or to make them apply to a template and all inherited templates
Low implementation effort, with high extensibility, maintainability and flexibility

Words of caution:

Don't make rules that filter the source based on the value of a field on the item (or even another item). If a change is made to the dependant field, the content author would need to save the item before the source filtering gets updated. Remember that a content author could have more than one window open too.
If you make rules that affect an item template and all inherited templates than any "overriding rules" must come after the initial rule, or the condition will need to be updated in the original rule to exclude the specific inherited template(s).
Answer: I would say no. Templates inheritance differs from code inheritance. If you create a field of the same name in an inheriting template Sitecore would not interpret this correctly.
The easiest answer is: if the source is different then the field itself is different thus you have to define it in the template where you are able to provide correct source.
But...
you can use getLookupSourceItems pipeline to process the source of a base template and try to parametrize it there.
Answer: As of Sitecore 7.0 with the introduction of The Buckets DLL, the code:<type, assembly> Template Field DataSource option was introduced that allows you to inject code to process your Datasource option.
I've used this in the past to programmatically determine datasource values.
In addition, if you'd like to see a full implementation of a custom datasource implementation that utilizes similar functionality, you can look at my Value List Field.
using System;
using Sitecore.ContentSearch.Utilities;
using Sitecore.Diagnostics;

namespace Sitecore.SharedSource.ValueListField.Pipelines.GetLookupSourceValueLists
{
    internal class CustomCodeSource
    {
        [UsedImplicitly]
        public void Process(GetLookupSourceValueListsArgs args)
        {
            Assert.ArgumentNotNull(args, "args");

            if (!args.Source.StartsWith("code:")) return;

            var values = RunEnumeration(args.Source);
            if (values != null && values.Length > 0)
                args.Result.AddRange(values);
            args.AbortPipeline();
        }

        private static string[] RunEnumeration(string templateSource)
        {
            templateSource = templateSource.Replace("code:", string.Empty);
            var valueList = ReflectionUtility.CreateInstance(Type.GetType(templateSource)) as IValueList;
            return valueList == null ? new string[0] : valueList.ValueListQuery();
        }

    }
}

Override the source of a template field


Does every greedy algorithm have matroid structure?

Question: It is well established that for every matroid $M$ and any weight function $w$, there exits an algorithm $\mbox{GreedyBasis}(M,w)$ which returns a maximum weight basis of $M$. So, is the reverse direction also true? That is, if there is some greedy algorithm, then there must be some matroid structure also.
Comment: Dijkstra's algorithm is often considered a greedy algorithm (e.g. see Section 4.4 of "Algorithm Design" by Kleinberg and Tardos).  I don't know of a matroid interpretation of single-source shortest paths.
Comment: Partitioning a set of real intervals into a minimum number of pairwise-disjoint subsets has a natural greedy algorithm (enumerate intervals by start time, for each add it to an existing subset if possible, else start a new subset; see Chapter 4 of Kleinberg and Tardos).  Can this problem be understood as a matroid?
Answer: Actually, the complete and general description of a problem that can be solved by a greedy algorithm is a matroid embedding, which generalizes both the concept of a matroid and that of a greedoid. The answer is no—a problem solvable by a greedy algorithm need not have a matroid structure, but it will have the structure of a matroid embedding (which is, alas, much more complicated).
A mental model for some of this could be finding minimum spanning trees. The structure used by Kruskal's algorithm is a matroid, but that used by Prim's algorithm (which requires a start node) is not. (It is, however, a greedoid—and a matroid embedding.)
Helman et al. (1993), in their paper An Exact Characterization of Greedy Structures define their notion of a greedy algorithm in terms of set systems, which is the same formalism that is used for matroids and greedoids. A set system $(S,\mathcal{C})$ consists of a set $S$ and a collection $\mathcal{C}$ of subsets of $S$, the so-called feasible sets. A basis for the set system is a maximal feasible set, that is, a set that is feasible but not contained in any other feasible set. An objective function $f:2^S\rightarrow\mathbb{R}$ associates each subset of $S$ with a value. An optimization problem, in this formalism, consists in finding a basis of maximum objective value for a given set system and objective function.
The greedy algorithm, defined in terms of this formalism, is quite simple: You start with the empty set, and successively add a single element until you reach a basis, always ensuring that (i) your set is feasible at each step, and (ii) the element you add maximizes the objective function of the resulting result, wrt. all the alternative elements you could have added. (That is, conceptually, you try adding all feasible alternatives, and choose the one yielding the highest objective value.)
You could, perhaps, argue that there might be other forms of greedy algorithm, but there are several textbooks on algorithms and combinatorial optimization that describe this set-system based algorithm as the greedy algorithm. That doesn't prevent you from describing something that doesn't fit, but could still be called greedy, I suppose. (Still, this does cover anything that could potentially have a matroid structure, for example, though it is much more general.)
What Helman et al. do is that they describe when this algorithm will work. More specifically:

They show that for linear objective functions (where the objective value is the sum of element weights), the greedy algorithm will work exactly on the structure they define as a matroid embedding;
They give a similar characterization for so-called bottleneck objectives (where the objective value of a set is equal to the minimum over the individual element weights); and
They give an exact characterization of which objective functions (beyond linear ones) are optimized by the greedy algorithm on matroid embeddings.
Comment: Can you explain what is their definition of a greedy algorithm?
Comment: Expanded my answer to explain what their formalism is.
Answer: Greedy algorithm is not a formally defined concept. There are various models trying to capture this intuitive notion but there is no consensus on what is a greedy algorithm. Unless you specify a formal definition of what you mean by a greedy algorithm the question cannot be answered as yes or no.
There is a generalization of matroids called greedoid which is inspired by greedy algorithms what you may want to look at.
Comment: A formal definition is not required if we agree on some property of the class of greedy algorithms. If, for instance, we agreed that every greedy algorithm has (a formally defined) property P, and we showed that every algorithm that satisfies P can be defined on a matroid, that would give a positive answer to the OP's question. Similarly, if we agreed that a certain algorithm is greedy and we showed it can't be the greedy algorithm of a matroid, that would yield a negative answer.
Answer: Consider following problems:
COIN-CHAINING EURO:
Given infinite amount of 1,2,5,10 euro notes, pay X euro using as few notes as possible.
This can be solved by using greedy algorithm, which takes largest note possible.
But there is no matroid structure in this problem.
HOLE COVERAGE:
There are holes in positions x_1, x_2, ..., x_n. You have patch of length 10 cm. Patch the holes using as few patches as possible.
Again this can be solved in greedy fashion (just put patch as right as possible), but there is no matroid structure.
Comment: There is a matroid structure for the coin-change problem - http://gauss.ececs.uc.edu/Courses/C671/html/Homework/hw5_sol.html
Comment: @user3373748 I usually just look for a dynamic program. Greedy is a degenerate DP.
Comment: (Not to be picky, but there are no 1- or 2-euro notes; you may want to change your set of values to {5, 10, 20, 50, 100, 200} or rephrase ;-))
Comment: thanks, i had my suspicions but was not sure. So after all we have to search for greedy algorithm even if matroid structure does not exist.
Comment: Note that the described coin-changing algorithm works for {1,2,5,10} but may not compute optimal results for other values. Example: With {1,3,4} the optimal solution for 6 would be [3,3] but the algorithm would return [4,1,1].


Can armored bx cable come into contact with other metal objects?

Question: I am running armored 12/2 bx to wire 4 high hats, the armored cable is grounded. There is a heating duct which I must go over, but the AC will come in contact with it... Is this ok or do I need to avoid having it make contact?
Answer: Armored cable is meant to resist damage to the conductors from contact with other materials (like a duct). The armor itself is grounded when properly installed, and touching other metal should pose no risk (assuming the armor is not so bent or compressed as to expose the conductors).
Answer: There is no such thing as BX cable.  Are you working with Type AC cable (armored cable), or Type MC cable (metal-clad cable)?
Metal-Clad Cable (Type MC)
Type MC cable has a grounding conductor, and the sheath cannot be used as a grounding conductor.
If you're working with MC cable, it's not likely any fault condition could lead to the ducting becoming energized.
Armored Cable (Type AC)
Type AC cable has an internal bonding strap, which is used as a grounding conductor.
If you're working with AC cable, there are indeed fault conditions where a duct in contact with the armor could become energized.  I'd try to avoid contact between the sheath and metal objects. In either case, make sure the grounding strap is properly bonded.
NOTE: The fault conditions required to energize the ducting would be, improper bonding, and a ground fault (current flowing on the sheathing).
Comment: "BX cable" is the product name of the original armoured cable, which has since been replaced by modern type AC. It's now used colloquially in the same way that "Romex®" (a brand name) is often used to refer to any Type NM cable.. in the same way people use "Kleenex®" to refer to any tissue paper. That said, when someone says "BX" it's not clear if it's AC or MC. In my region I typically only ever come across MC (I don't think the box stores even sell AC), and I used to always call that "BX" as everyone else I knew did.
Comment: @gregmac -- modern type AC is still made and sold...
Answer: Apart from electrical considerations, one should avoid having dissimilar metals in long-term contact, especially in what could be damp or humid conditions.  Electrolytic corrosion could compromise one or the other of the metals.  That's why, for example, you need to use copper clamps and copper nails to fasten copper water  pipe...
Comment: This is correct.  Avoiding any contact with copper water pipes is recommended.
Answer: When properly installed the cladding of both AC and MC cables are always grounded (in most cases using identical connectors) and both cable types have always been installed in contact with most of the usual conductive building materials: steel studs, structural steel, ducts, plumbing and so on. And because Armored Cable has the bonding strip, its sheathing would have the lower resistance of the two cable types making it the safer one if its sheathing had to conduct a fault current.
Because many more people know exactly what you mean when you say Romex, I prefer the word. When it comes to the terms BX , AC or Armored Cable, it depends on who I'm talking to and it also depends on whether it's the old steel stuff or the contemporary aluminum. For the old stuff, because more people would know what I mean, I'd be more likely to say BX and reserve the terms AC or Armored Cable for only when referring to the newer stuff and talking to someone who knows what it is.
Why Armored Cable? Is this your home? Is it elsewhere wired in Romex?
Why #12 awg? Is it a 20 amp circuit?
What kind of Armored Cable do you have? Is the sheathing aluminum? Is there a full size bonding strip? Is there a green insulated copper ground conductor?


Is one allowed to read programming books on shabbos?

Question: If one is a software engineer by profession, is one allowed to read programming books granted one receives pleasure from doing so?
Comment: it might be useful to clarify if you are reading for pleasure or for work (work being primary, pleasure being secondary)
Comment: I think that is part of the tricky thing about programming books. Is that it is for pleasure, but it will undoubtably be helpful for work as well.
Comment: related https://judaism.stackexchange.com/questions/79485/studying-for-a-test-during-shabbos
Comment: see my answer below where the need for parnasa makes it easier to permit - always good if you want to [edit](https://judaism.stackexchange.com/posts/86582/edit) your question to make it as precise as possible for others to help as well
Comment: Isn't this considered Metzo Chefzeycha ? See Shulchan Aruch OC 306. Even not for work, doesn't a great part of the pleasure come from {dreaming about typing this a day} => {thinking, in an *apparent* manner, about something forbidden in Shabbos}? [A software engineer's answer ;-)]
Answer: In general reading secular literature on Shabbat is discouraged but not forbidden - it should be a day focused on learning Torah. Here are a few opinions on the topic
R Jonathan Blass on students studying on Shabbat

It is permitted on Shabbat to read secular school books but, if
possible, this should be minimized (Shulchan Aruch Orach Chayyim 307
17; Mishna Berura 307, 65) [...]

see also here
R Shlomo Aviner writes

This is a dispute between the Rishonim. The Rambam wrote in his
commentary on the Mishnah (Shabbat chap. 23 and quote in the Beit
Yosef Orach Chaim 307) that it is forbidden to read books of wisdom,
which are not Torah, on Shabbat and Yom Tov. This is interesting since
the Rambam is usually thought to be the authorities most open to
general wisdom. But according to the Ramban (Beit Yosef ibid.), it is
permissible to read medical books since they contain wisdom.
These two
opinions at quoted in the Shulchan Aruch (ibid. #17): "It is forbidden
to study on Shabbat and Yom Tov aside from words of Torah, and even
books of wisdom are forbidden, and there is an opinion which permits
it." The Mishnah Berurah (380:65) indicated that we act leniently but
it is proper to be strict.
The basic halachah is therefore that it is
permissible to learn secular subjects on Shabbat but it is certainly
proper to be strict. If one follows the permissible view, it includes
school reading or studying for a test on the condition that one enjoys
it. If such activities cause stress and fear over a test, one should
refrain from studying.

DailyHalacha writes

The Shulhan Aruch (Orah Haim 307:17) writes, "It is forbidden on
Shabbat and Yom Tob to study anything besides words of Torah; even
scholarly matters are forbidden. But there is [an opinion] that allows
it" (listen to audio recording for Hebrew citation).
The first view
recorded in the Shulhan Aruch forbids reading all secular material,
including scholarly textbooks, whereas the second view – which is the
position taken by the Rashba (Rabbi Shelomo Ben Aderet of Barcelona,
1235-1310) – permits studying "Dibreh Hochma" – works of scholarship.
(This is also the position of the Ramban.)
There is a general rule that when the Shulhan Aruch records two views
in this fashion ("Setam Va'yesh"), he accepts the first opinion as the
Halacha. Accordingly, it would be forbidden to read or study any
secular material on Shabbat or Yom Tob, including secular textbooks.
The question arises as to whether this would apply to consulting a
medical textbook for guidance in treating an ill patient on Shabbat.
If, for example, a doctor is called upon to treat a patient on
Shabbat, would he be allowed to review material in his medical
textbooks for verification? For that matter, if a child is sick, may a
parent consult a medical guidebook to determine how to best treat the
child?
Hacham Ovadia Yosef, in his work Halichot Olam, writes that in such
cases one may rely on the lenient view of the Rashba, who, as we saw,
permits studying secular subjects on Shabbat. Since there is a
particular need to study the material in question, we may, under the
circumstances, rely on the Rashba's position. Hacham Ovadia applies
this ruling even to a medical student who will be taking an exam after
Shabbat. Given the present need to review the material, the student
may rely on the lenient view of the Rashba and study for his exam on
Shabbat.
This discussion should alert us to the importance of devoting our free
time on Shabbat to Torah study. Even when it comes to reviewing
medical information, Halacha permits this study only on the basis of
the minority view of the Rashba. Certainly, there is no room to permit
reading novels and other unnecessary material on Shabbat, and
reviewing one's bills and other financial papers is most definitely
forbidden on Shabbat.
Comment: I find that the case of physicians is rather an exception, since many times they need to work on Shabbat for pikuach nefesh. I suppose the relevant point is whether one's allowed to read things related to her/his job - assuming that you accept the lenient view and you're not a rabbi :-)
Comment: @mbloch There are other opinions which hold pleasure reading is allowed. http://halachipedia.com/index.php?title=Reading_on_Shabbat my hahaha rebbi gave a shier about reading on shabbos abd also quoted another source permitting it (I think rav auerbach). Something about how books are different. Perhaps that part of the shier was on lists though. I'll check it up and update.
Comment: @Orion I also quote many sources holding it is allowed (even if discouraged). The link you provided, esp. note 8, show clearly this is not forbidden but many limit it. Permitted or allowed doesn't mean it is a good thing and that is a distinction many *poskim* make
Comment: @Mbloch No you quoted many which agree it is permitted to read secular chochma. Not pleasure reading. Your last quote from daily halacha said there is no room to allow secular books for pleasure. I'm pointing out that this is not technically true as there are those that hold reading novels for pleasure is permitted.


What's the most efficient way to select workers to build things in Starcraft 2?

Question: When I'm building up my base, I sometimes find myself wasting time trying to get a single worker off of my resource line so that I can build something. I often miss or have to chase after them if I'm trying to single click, and dragging often selects more than one, at which point I have to try again or click on one in the selected units list. It seems like it would be best to grab one right after it's returned its resource and is heading back for another, but they're also moving the fastest at this point. It's easier to grab them while they're mining, but then they're carrying resources around and this feels wasteful. Is this minor optimization unnecessary, or am I missing something? Should I just keep a dedicated builder idle for easy selection (as terran or protoss)? Put one on a hotkey?
Comment: sigh.  no chance of hotkeying a worker for us zerg players.  our workers really put their 'all' into each building.
Comment: @Peter my zerg strategy is as follows: Never stop building drones.  Its a little out there, I know, but I find it serves me well.
Comment: @Peter but we can smart cast a bunch of buildings and not have to worry about queuing up other commands.
Comment: @tzenes true.  and then (if you're me) wonder why our income is so low, and finally remember to crank out a bunch more drones :)
Answer: So obviously selecting 1 is better than a group, but a little known fact:
Workers smart cast!
This means if you select a group of workers and try to build something, the nearest worker (and only him) will go to build the building.  Additionally if you build more than one thing, the two nearest will go to do the task.  This means you don't need to worry about selecting more than one (provided you don't issue any move orders), just select the group and build away!
Comment: Actually you should never take advantage of smart casting due to the fact that when you select the worker you should not have the minerals ready needed to build the building.
Usually it works like this: You select the worker and bring him in position, timing it so that only once he reaches the desired building spot you have enough minerals to start building. If you wait for your workers to be able to smart-cast the building you'll have unspent resources and be slower..
Comment: @Tigraine I 100% agree with you.  If you are a top player you should never have enough minerals to build what you want when you select a worker.  On the other hand if you are a player who has trouble selecting one of his workers from the mineral line, chances are smart casting will really help you.
Comment: @Kyralessa the other 3 (who aren't building) have the action of "harvest" until they are finished with it (all patches are empty) they won't follow the queued command; so there is no real loss.
Comment: @tzenes I think what she's asking is "how do you handle sending the SCVs who are building back to the mineral line when they're done?"
Comment: @McKay She's asking that if you select 5, tell 2 to build and queue up the action of going to a single mineral patch, will the workers who aren't building all head to the same patch.  The answer is no.  They will finish their current action before following the queued command.  Since their current action is "harvest" not, "harvest 5 minerals" or "harvest only from this one patch," they won't finish that task until all minerals are gone, at which point the queued command is no longer valid.
Answer: Don't select all your workers and use smart cast, make sure you only grab workers that are on minerals. You don't want to pull a worker from gas and then later put him back on minerals. You'll be short a worker on gas, which is very easy to miss.
In the early game, when there isn't that much to do, you should get used to selecting a worker individually on his way back from mining, then watch him drop his resources off, and then tell him to build. This is better than smart casting. Later on when you've got a lot to do this'll be way too time intensive, so at that point you can switch to using smart casting.
Also, tell your worker to build the building, and then shift right click on your minerals. That way he'll go back to mining the moment he's done, which means no time is wasted.
Comment: This is not as much of an issue anymore, as the extractor/assimilator/refinery shows how many workers are working in it.
Answer: No, don't have any builder idle if you can help it. Really I just single click, I know you tried this but I would guess that is the best way to get just one. Just spam click if you have to until you get one, eventually you'll get better at aiming anyways.
Another note: If you hit F1 it will select a worker who is doing nothing!
Comment: Note: A worker should never be doing nothing is part of a winning strategy
Answer: I do the shift-cntl f1 at game beginning to select all probes and send them to mine.
Then I select 1-2-3 probes and put them in groups 1 2 and 3, which serves as builder, expansion, scout as the game goes on.
Answer: After watching a lot of starcraft 2 replays, I've learned to single-click a worker early in the game and bind him to a hotkey for whenever I need him. Although having read that workers smart-cast, I may stop doing this and just double-click to select them all.
Comment: Since workers are generally continuously moving, ctrl+clicking may be easier to select them all.
Answer: What you can do is set up one worker to a bind Ctrl + 1-9 Then every time you press just 1 and it selects that unit.
This can be done with any unit, therefore a lot of people use it for their Void Rays etc etc
Answer: Using the Hotkey has the advantage of being able to build things while your workers are not visible on the screen.
I just bind 3 (sometimes more) workers to a hotkey.
Answer: One note to make if you select 5 workers and hit B(build) S(supply depot) and click where to build only 1 scv will go to build it even though you selected 5. Obviously this still works no matter what you build but you don't have to just select one you can select any number of them and just give one command. Each command you give after that the next one will go and do the building.
Comment: I know you're new, but please try to read through the answers before posting.  You'd notice someone wrote this 12 hours before you...


Will Voyager 1 or 2 be able to take photos?

Question: Will Voyager 1 or Voyager 2 be able to take a photo of their current view, using their cameras and send the photo to Earth? Do they have the power to do this?
Answer: From the Voyager FAQ

Question: Can the Voyager imaging cameras be turned back on?
Answer: It is possible for the cameras to be turned on, but it is not
  a priority for Voyager's Interstellar Mission. After Voyager 1 took
  its last image (the "Solar System Family Portrait" in 1990), the
  cameras were turned off to save power and memory for the instruments
  expected to detect the new charged particle environment of
  interstellar space. Mission managers removed the software from both
  spacecraft that controls the camera. The computers on the ground that
  understand the software and analyze the images do not exist anymore.
  The cameras and their heaters have also been exposed for years to the
  very cold conditions at the deep reaches of our solar system. Even if
  mission managers recreated the computers on the ground, reloaded the
  software onto the spacecraft and were able to turn the cameras back
  on, it is not clear that they would work.
In addition, it is very dark where the Voyagers are now. While you
  could still see some brighter stars and some of the planets with the
  cameras, you can actually see these stars and planets better with
  amateur telescopes on Earth.

Bottom line, it might be able to happen, but not really. The cameras are probably damaged due to exposure to the cold of deep space, and the cameras wouldn't do much good anyways.
Answer: These were the last photos Voyager 1 took, on February 14, 1990:

This became known as the "Pale Blue Dot" photo.
And the Solar System Family Portrait:

Voyager 1 had traveled 6 billion km at that time. After these images were taken, the camera was shut down as @Pearson says.
Voyager took 60 photos. This shows all of them:

On some of the photos, you can see rays of scattered light from the Sun. Because Earth is relatively close to the sun, these rays are visible in the Earth image.
High-resolution version of the mosaic
According to this list of Voyager 2 photos, Voyager 2 took its last photo of Neptune on 1989-09-29:

In 1998, the scan platform (which contains the cameras) was shut down, as not enough power was available to operate it any more. This means that even if the cameras could be powered up again, there's no way to aim them.
Comment: what about voyager 2 ????
Comment: @ReNiShAR voyager 2 being older than voyager 1, there is no way it still have power :)
Comment: Are voyager 1's cameras still facing the general direction of the Sun even when shutdown?


If I take a loss when I sell my car, can I claim a capital loss deduction on my income tax return?

Question: If I sell my car off at a loss, can I write that loss off against my income to save on tax? Does it matter if the car was used just for personal leisure use, or if I used the car to generate business income? (e.g. travel to work, to attend education seminars, etc.)
Answer: While you'd need to pay tax if you realized a capital gain on the sale of your car, you generally can't deduct any loss arising from the sale of "personal use property". Cars are personal use property.
Refer to Canada Revenue Agency – Personal-use property losses.  Quote:

[...] if you have a capital loss, you usually cannot deduct that
  loss when you calculate your income for the year. In addition, you
  cannot use the loss to decrease capital gains on other personal-use
  property. This is because if a property depreciates through personal
  use, the resulting loss on its disposition is a personal expense.

There are some exceptions. Read up at the source links.
Comment: Have a look at [Form T777 (PDF)](http://www.cra-arc.gc.ca/E/pbg/tf/t777/t777-13e.pdf) ... the middle section on the first page is for calculating your allowable automobile expenses. Line 9 is the capital cost allowance, and the next page in the document describes how to calculate it. You'll also want to refer to [Guide T4044 (PDF)](http://www.cra-arc.gc.ca/E/pub/tg/t4044/t4044-lp-12e.pdf). Note that if you are an **employee**, you can only claim such expenses if your employer provides you with a T2200 slip permitting such. Only some kinds of employees can deduct car expenses -- most cannot.
Comment: Thanks a lot. But if I use the car to generate income (i.e get to work, lease it out for a day), is it still considered personal use or does it qualify as business expense?
Comment: The loss on the sale of the car doesn't qualify as a business expense. If you were claiming a portion of your car expenses as a business expense, you would have had an opportunity, each year, to claim a portion of the Capital Cost Allowance (CCA) for the vehicle. CCA is a form of depreciation. Did you do that?


Replacing Nautilus with Awesome Windows Manager on 12.04

Question: Just like the title suggests, any idea on replacing nautilus with Awesome WM?
Answer: I think you are confused. Awesome WM, as the name says, its a complete window manager. On its side, Nautilus is a file manager. Anyways, this can be what you are looking for.
Answer: Windows managers are those programs which provide the windowing functionality, such as title bar, window border, moving, resizing etc. And Awesome is a window manager, which is lightweight in resource usage.
On the other hand, a File manager is a program which provides you facility to browse or navigate the file system, move, copy, create files etc. And Nautilus falls in the category of file managers, it's not a window manager. In fact, Nautilus is the most loved and used file manager in Linux desktops.
There cannot be any question of replacing a window manager with a file manager. But, yes, you could ask to replace Compiz (which is another window manager)  with awesome window manager or replace nautilus with another file manager such as Thunar.
Answer: You can install and use other file manager such as PCManFM or Dolphin in Awesome WM. And there is also a file manager in terminal like Ranger.


How to use Drush in remote server?

Question: I'd like to use drush methods in the remote server.
As far as I know I have to install Drush in the remote server.
But my server provider tell me that Drush has many conflicts with other modules that the server is already running. How do you manage to use Drush in remote server? Is my server provider answer acceptable?
Comment: Sounds like they're worried about installing Drush because they don't know if it'll cause problems. But, if they're managing the server, you've kinda got to respect the decision that they make. After all, if installing Drush does mess something up then it's on _them_ to fix it
Comment: Hmmm that sounds a little fishy...could you ask them to specify _which_ of these other modules the server is running that conflict with Drush? And how they conflict? That might help to confirm whether their statement is fair or not. For the record, I've never had a problem installing/using Drush on any server (although I've never tried to get it on a shared host before)
Comment: I'll try to deep into this. It is a **Managed Dedicated Server** (not shared). They told I can install myself if I change to a **Not Managed Dedicated Server**.
Comment: I allready managed to convince some clients' managing providers there is no harm. And i am quite convinced there really aint. Basically - drush is a set of php files. All it needs is php cli, which shouldnt be a problem.
Comment: my server provider is pretty strict about this. No explanation at all. If I want Drush installed I have to change from managed to unmanaged server. Closed.
Answer: It is possible to use Drush with a Drupal site that is running on a remote server that does not have Drush installed.  This is possible because the Drush commands drush rsync and drush sql-sync work by composing ssh commands; if you set up your site alias configuration carefully, then you can copy your site to a local machine to operate on it.
In order for sql-sync to work without Drush on the remote system, you must define the 'databases' and '%dump-dir' variables in your site alias.  Otherwise, Drush will try to use Drush on the remote system to look up these values.  See example.aliases.drushrc.php for more information.
Note that it is really useful to be able to at least run drush updatedb on the remote server, so that you can update your database after you rsync new code over. Of course you can do this through the GUI too, but Drush is faster.  The Resources page on drush.org lists some hosting providers that are Drush-friendly.
Comment: very helpful. By your words I understand that I have to work on local server and keep it sync with the remote server by using the methods: `drush rsync` and `sql-sync` but won't be able to run `drush updatedb` on remote server if drush is not installed in remote server. Do I need to put the drush folder (the tar.gz file) in my server as **yvan** mention in the answer below?
Comment: There is info on how to install Drush in the README.txt file at http://drupalcode.org/project/drush.git/blob/HEAD:/README.txt. See also this recent blog post on the subject: http://robinmonks.com/2012/05/installing-drush-on-a-mediatemple-gs-grid-service-account/.  Please avoid the Drush-5.3 release; it was recently released with some bugs. Use 5.2, or HEAD of the master branch in git.
Answer: If you've any SSH access you can install Drush by yourself. Simply download the tar.gz from drupal.org and untar it into a folder on your server. Then you may add execution rights to drush/drush and you will able to use Drush perfectly (simply you just need to add all path before the command, for example /var/www/drush/drush updb).
Like others said, you should ask more informations about the conflicts and tell them that it's totally absurd that Drush create conflicts with other modules as it's require only php-cli.
I already installed drush on some servers and even on shared server and it works perfectly as you've SSH access.
Comment: I'll try. I understand that I won't need any installation at all on remote server, I just need to upload the drush folder. Am I right?
Comment: Yes, you're right
Comment: I'm following this but I can't get it working. This is what I did: 1) put drush folder in `www/`then I have this path to the drush file: `www/drush/drush` 2) I change the permisson of drush file to 777 3)I run this method: `www/drush/drush status` and I get this message: `www/drush/drush: line 26: /bin/uname: Permission denied`. But something is working because below this error message I get these lines: `PHP configuration     :  /usr/local/lib/php.ini` || `Drush version         :  5.3` || `Drush configuration   :  `
Comment: Done. I got it running just fine. But it still shows this message every time I run a method just above the results: `drush/drush: line 26: /bin/uname: Permission Deny`
Comment: It's not a big deal this error as `uname` is just a command to get the name and version of your os. Seems to be its one limitation from yours hosting company.
Answer: Alternatively this module may allow you to use Drush on a remote server without asking your host provider to install it: https://drupal.org/project/drushweb
Some details from the module's project page:

This module allows to run Drush without being granted access to the machine it relies on. It may be useful on shared hosts that do not provide SSH access to servers.

How to use Drush in remote server?


counters for weight?

Question: After looking online, I found a counter supposedly for grams: 匁(monme). Is this  right? Also, would I just use it with the noun + particle + counter + verb form? Like 食べ物の一千匁をもって来る.
Answer: 匁 is an old Japanese unit for weight and it's approximately equal to 3.75 g. See: Japanese units of measurement. It's almost never used today, and you can probably forget it for now.
To refer to grams, you have to say グラム, which is just a transliteration of 'gram'. Actually there is a kanji for 'gram', which is 瓦. But this is also almost never used in modern Japanese, and you should not use this.
When you want to use の, the correct syntax is number + unit + の + object (e.g., 5冊の本, 3人の先生). The correct sentence would be:

1000グラムの食べ物を持ってくる。
  I bring 1000 grams of food.

Alternatively you can avoid using の and say:

食べ物を1000グラム持ってくる。

See the discussion here: How to list numbers of things
(I used Arabic numerals which are usually preferred in horizontal writings)
Answer: As in other languages, Japanese has various ways to express weight. The most popular terms are キログラム (kilogram) and グラム (gram).  キロ is broadly used for キログラム, but you should note that it could also mean キロメートル (kilometer) and キロワット (kilowatt) depending on context.
[匁]{もんめ} is tricky and as far as I know, it is mainly used to refer to weight of precious metals such as gold or silver.
[斤]{きん} is 600 grams and it is mainly used for bread or meat.
You can read the linked Wikipedia article on Japanese units of measurement.

counters for weight?