Confused about pumping lemma, What i'm missing? When I apply pumping lemma on this language: 
${L=\{010^n:n\ge0\}}$ over the alphabet ${\Sigma =\{0,1\}}$ I get that it is non-regular despite the fact that it is regular.


let ${n=4}$, then $w=010000$
$w=xyz$ ,  $ { \mid xy\mid \leq n} $ and $ {\mid y\mid \geq 1}$ 
$x=0$ , $y=10$ , $z=000$
let $i =2$
$xy^2z = 01010000$ $\not\in L$ so L is non-regular.


so, what I'm missing?
you can't claim to know how $w$ distributes.

you know that some $w \geq n_0$ exists, in such a way it can be denoted as 

$w=xyz$

$y \neq \epsilon $

$ |xy|\leq n_0 $

and for every $i&gt;0: xy^iz \in L$

your error is that you claimed you know the distribution of $w$ to $x,y,z$. Namely, you fixed $y$ to be $10$

The language of course can be pumped, since it's regular. But for any $w = xyz, y$ must be a word of only $0$, since $1's$ cannot be pumped.