I have a claim I need to prove or disprove. Let Sk(A) be the Skolemization of A (A is a sentence). If Sk(A) is valid then A is also valid.
In other exercise I was asked if A is valid then Sk(A) is also valid, but I think I disproved it with a counter example(if it is right then please let me know hehe)
I think that its true that if Sk(A) is valid then A is also valid, but I don't know how to show that.
Any ideas where to start?