How can I prove that:
If a formula A is provable without use of substitution axioms, nonlogical axioms, equality and identity axioms, and the \exists-introduction rule, than A is a tautology.
I try to act this way: consider a tautology A and show that using propositional axioms I get...
Why these two tensor products are isomorphic?
Hom_{K}(V,K) \otimes Hom_{K}(V,K) and Hom_{K}(V \otimes V,K)
where K is a field and V is a vector space over K.