logical implication

Geetha has a conjecture about integers, which is of the form $$\forall x\left( {P(x) \Rightarrow \exists yQ(x,y)} \right)$$, where P is a statement about integers, and Q is a state...

Consider the first-order logic sentence $F: \forall x(\exists y R(x, y))$. Assuming non-empty logical domains, which of the sentences below are implied by $F$? I. $\quad \exists y(...

Consider the following expressions: $$\,\,\,\,\,\,\,\,\,\,\,\,\,$$ $$(i)$$ $$\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,$$ false $$\,\,\,\,\,\,\,\,\,\,\,\,$$ $$(ii)$$ $$\,\,\,\,\,\,\,\,\,\,\,\,...

Which one of the following well-formed formulae in predicate calculus is NOT valid?

Let $$p$$ and $$q$$ be propositions. Using only the truth table decide whether $$p \Leftrightarrow q$$ does not imply $$p \to \sim q$$ is true or false.

Which of the following predicate calculus statements is/are valid?