# Is the validity of the Skolemization of a sentence A infers the validity of A?

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?

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What does valid mean? In a given $L$-structure? The language has changed, and one technically needs to provide an interpretation for the new constant symbols/function symbols. However, under any such interpretation, if the Skolemization is valid, then the sentence is. –  André Nicolas Dec 14 '12 at 19:33
"I was asked if A is valid then Sk(A) is also valid, but I think I disproved it with a counter example" Example? –  Peter Smith Dec 14 '12 at 20:18