Once I complained to one of my undergrad math professors that I was hopelessly lost when it came to combinatorics and combinatorial probability problems. He remarked, half-jokingly, that combinatorics was tricky until you started solving them as a special case of (blank), which to me sounded very abstract and modern.
But for the life of me I can't remember what (blank) was. What could it be? If it matters, I think his field was algebraic topology, but he was (still is) an old dude that just knows a heck of a lot of stuff.
For the record, I was mostly hoping to point to get an answer that would contribute to Problems that become easier in a more general form.
