Contraction of ~ている


I've seen some examples of ~ている contractions, like

> この世は腐{くさ}ってる。

1) Is this a common occurrence?  
2) How does this affect the formality of the sentence?  
3) Is there a "rule" for the いる verb? Meaning, does the verb also contracts in
other conjugations?




It is very common in both speech and writing. Its use certainly lowers the
level of formality, although it's common enough that you might even use it in
situations that would normally be considered more formal, like with colleagues
at work.

I don't think this falls under a broader set of rules; it's just a written
representation of something that often happens in speech simply because it's
easier to say. It is related to the similar phenomenon of ら抜き言葉, like 食べれる
instead of 食べられる.




It is very common in both speech and writing. Its use certainly lowers the
level of formality, although it's common enough that you might even use it in
situations that would normally be considered more formal, like with colleagues
at work.

I don't think this falls under a broader set of rules; it's just a written
representation of something that often happens in speech simply because it's
easier to say. It is related to the similar phenomenon of ら抜き言葉, like 食べれる
instead of 食べられる.

