Section A_declared. Variables (A : Set ) (P Q : A->Prop) (R : A->A->Prop).Prove the following theorems:
(forall a b:A, R a b) -> forall a b:A, R b a (forall a:A, P a -> Q a) -> (forall a:A, P a) -> forall a:A, Q a (forall a b:A, R a b) -> forall a:A, R a a