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Proving Tautologies

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State

Tautologies are provable from zero premises — open immediately with a CP or IP assumption.

Show

To prove p ∨ ~p: assume its negation, De Morgan it into p-and-not-p territory, explode, discharge.

Watch for

A proof with no premises looks impossible for exactly one video's worth of time.

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Unlocks

  • Nothing yet depends on this.