assignment completed

I just had a nice session with my partner and we wound up neatly typing up our very informal solutions to whats now a very presentable proofs to our TA's. I believe we have done a decent job in all the questions. I however feel skeptical about how assured a potential skeptic might feel about our proofs to question 2. In particular proving that language L with even number of 1s is also a subset of the regular expressions was personally very hard to prove. I guess i in general struggle to prove theorems or lemmas which seem intuitively obvious at the first glance and cant automatically generate proofs for then at the top of my head. Having had Danny as a course instructor for 2 courses now, i realise how anal he is about simple intermediate steps ( for example, we always have to mention that addition is closed!! ) so i wont be surprised if we loose a couple of marks on question 2.