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Sun 29 Oct, 2017 04:23 pm
(~ A v B) > ~ C , D > ~ A , D & E ⊢ ~ C & E
@kdj7795,
What step are you hung up on?
Look up the rules of inference called specialization and generalization.
@Kolyo,
Kolyo wrote:
Look up the rules of inference called specialization and generalization.
Not all books call those rules that. The first is sometimes called simplification and allows you to conclude 'D' from 'D and E'. The second is sometimes called addition and allows you to conclude 'X or Y' from just X. Start your proof by using simplification on 'D and E' to conclude 'D'.
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