How is it that "p implies q" is equivalent to "not p or q"?
50733
Help to understand material implication
142762
how to prove that (P⊃Q)≡(¬Q⊃¬P) ( P ⊃ Q ) ≡ ( ¬ Q ⊃ ¬ P ) is disallowed in intuitionistic logic?
150053
Is "$(P \land Q) \to P$" a tautology?
67394
How to interpret $\mathbb{P}(B|A)$ when $\mathbb{P}(A) = 0$
34045
3 Statements of axiom of choice are equivalent
121361
Showing that $\lnot Q \lor (\lnot Q \land R) = \lnot Q$ without a truth table
62936
Proving equivalencies of two versions of the Axiom of Choice
147375
Prove :(P → Q) ∨ (Q → P) using natural deduction
56351
Prove that these statements $(A \lor \neg B)$ and $\neg A \to \neg B$ are logically equivalent
65379
Deriving $\neg R$ from $\{R↔(R∨(P∧¬P)), R↔¬P, ¬P→(P↔(Q→Q)), P→Q\}$
140194
Using natural deduction to prove that $p \implies q \vdash \lnot p \lor q$
35370
Why is this proposition provable and its converse not?
116527
Validating a proof for necessary and sufficient conditions on sets A & B such that $P(A) \cup P(B) = P(A\cup B)$
85770
What is the difference between ∀x(p(x) →q(x)) and ∀x(p(x) ∧q(x))?
70166
Why is the universal quantifier $\forall x \in A : P(x)$ defined as $\forall x (x \in A \implies P(x))$ using an implication?
132423
Non trivial valuation over a finite extension $F/\mathbb{Q}_p$ is equivalent to the one induced by $v_p$
13074
Prove Logical Equivalence