New posts in Propositional Calculus

Without constructing a truth table show that the statement formula ~(~p→~q)→~(q→p) is a tautology

How to solve for $x$ given $x⇔A$ in a truth table?

Does double negation distribute over implication intuitionistically?

Is law of excluded middle necessary in this proof?

Why does $AB + BC + CA = (A\oplus B)C + AB$ not imply $BC + CA = (A\oplus B)C$ in boolean algebra?

$ \models A$ vs. $ A \models$

On the reiteration (or repetition) rule in natural deduction: is the rule "obvious" or does it need a proof?

Negation of a Basic Logic Statement

Solving a Smullyan style knight and knave problem using natural deduction. How to shorten this proof?

Logic - How to say "Not only but also".