I am initiating myself into TOC and using sort of random resources from the web. I was looking at this problem from a Berkeley problem set: Construct a PDA to accept $ L = {a^ib^j|i \neq j , 2i \neq j} $ And I don't understand the given solution here.(Problem 4) http://www.cs.berkeley.edu/~isabelle/cs302/ps3-solutions.pdf
When can we say this machine accepts a string? From my understanding, it seems to accept ab,aabb,aaabbb etc as well when it shouldn't.