New posts in Propositional Calculus

Proof of $\bot \Rightarrow p$

How does one visualize propositional logic?

Need to prove $(p \land q) \land (\lnot p \lor r) \rightarrow (q \lor r)$ is a tautology.

Prove $\neg (p \land q) \vdash \neg p \lor \neg q$ by natural deduction

Simplify, equivalent for (p ∨ ¬q) ∧ (¬p ∨ ¬q)

Natural Deduction Proof for Modus Tollens

Understanding ex falso quodlibet together with proof by contradiction in a Gentzen style ND Proof

Is there a general effective method to solve Smullyan style Knights and Knaves problems? Is the truth table method the most appropriate one?

Are " replacement rules" and " inference rules" ( in natural deduction) really two kinds of rules?

Prove $\vdash (A_1 ↔ A_2) \vee (A_2 ↔ A_3) \vee (A_3 ↔ A_1) $ using natural deduction.