Is there manual solutions for <Computational Complexity A modern approach>?

@闫伯元 I don't think so, but if you have a specific question, you could always try asking on the main site

@Raphael Re this answer, regular langauges are closed under concatenation and reversal, so it seems pretty immediate to me. Am I missing something?

@DavidRicherby Maybe I'm going about it in the wrong direction. I get to $\{y^R \mid xyz \in L\}$, but then I'm stuck.

@Raphael It's just the concatenation of L, L^R and L.

@DavidRicherby I hear your ansatz, and I raise you a prefix-free $L$.

@Raphael Oh, wait. I misread the question. xyz\in L, not, as I read it, x,y,z\in L.

It took me one month to understand the working of BitTorrent

@DavidRicherby Phew. :'D

@defalt I once saw elephants do it.