Tautology checker

How to use this calculator

Edit the formula inside IsTautology. A proposition or its negation is a tautology.

Tap the math below to edit it and see the result. Once a result is ready, press Tab on a hardware keyboard to accept it. Outside a matrix, Return completes the line; the phone math keyboard has the same Return action.

Try it here

Interactive tools require JavaScript. You can read the guide and example without it.

What to know

This is propositional logic, not a general quantified theorem prover. Large formulas can exceed time limits.

Mathlean combines visual mathematical input with computation and canvas tools. Results depend on the expression and available engine support; check important answers independently.