6.5.2 Predicate calculus

Problem: Establish the truth of the logical expression using two methods: 1) by defining quantifiers and 2) by the method of concretization. a) \( \forall x \exists y(A(y) \vee B(x))=\exists x A(x) \vee \forall x B(x) \), b) \( \forall x \exists y P(x, y) \Rightarrow \exists x \exists y P(x, y) \).