Logic / Unit 5 Logic 196 short lesson, about 20 seconds
Disjunctive Syllogism as a Proof Move
Captions available
The idea
From p ∨ q and ~p, derive q.
In practice
1. A ∨ B. 2. ~A. 3. B (1, 2, DS).
Where people slip
Deny a disjunct to release the other. Affirming a disjunct releases nothing (155) — the proof system won't even let you write it.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
Builds on
Unlocks
- Nothing yet depends on this.
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