What would the Philip Roth of Squirrel Hill look like? That is the premise (or one of them) of Lisa Halliday’s “Asymmetry” (Simon & Schuster, $26). Ms. Halliday’s main character, Ezra Blazer, is from Pittsburgh, not Newark, N.J., and his character is an animated version of Mr. Roth for good reason — the author worked for eight years at The Wylie Agency, which represents Philip Roth.