top | item 17163771

(no title)

lactau | 7 years ago

Sounds like dilemma: https://en.wikipedia.org/wiki/Dilemma#Use_in_logic

discuss

order

a-nikolaev|7 years ago

Disjunction elimination rule of inference: https://en.wikipedia.org/wiki/Disjunction_elimination (plus, the law of excluded middle that either E or not E holds)

thaumasiotes|7 years ago

Wow, that rule is stated horribly.

You'd get much more value from phrasing it as

    ((p implies r) and (q implies r)) iff ((p or q) implies r).
No need to have a special rule stating that when you also have (p or q), you can resolve all three to just "r" in one step instead of two steps.