answer:First, I’d say the phrase “neither X nor Y” should be translated as “not-X and not-Y” = ¬X ∧ ¬Y rather than “not (X or Y)” = ¬(X V Y). They are equivalent by DeMorgan’s theorem, but that’s an additional step. As for your main question about using variables vs. constants, I don’t know predicate logic in this context. You could try formulating it as something like, “For all classes c there exists an s such that not P(s, c, math) etc. but that might be wrong. Can’t find it at Wikipedia or Wolfram mathworld. I’d work from examples given in your reading material.