I have looked at Wikipedia(I know it's not completely reliable) but on it an operation is formally defined as: "A function ω is a function of the form $ω : V → Y$, where $V ⊂ X_1 × … × X_k$." and I have also heard one of my professors mention in passing that an operation is a "special" kind of function.
Here's the thing, functions have only one output and therefore operations should too, however the indefinite integration operation has infinitely many outputs if the antiderivative exists. Can you please clear this up for me, perhaps the definition of an operation is wrong? And if so what is exactly an operation then? Thank you very much.