I don’t know his last name. He has significant Autism (I didn’t catch the details when he told me about it, it was some specific type). I met him on Saturday, while trying to make some ground on a math project at my favorite cafe. I pulled out a book, and he couldn’t help but notice the publisher (good ‘ol Springer-Verlag…they’re the primary publisher of math texts, and they nigh always bind with a signature yellow cover), so he asked me what I was working on, and we proceeded to talk about math for a while.