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Mirrors > Home > MPE Home > Th. List > notnotrd | Structured version Visualization version GIF version |
Description: Deduction associated with notnotr 125 and notnotri 126. Double negation elimination rule. A translation of the natural deduction rule ¬ ¬ C , Γ⊢ ¬ ¬ 𝜓 ⇒ Γ⊢ 𝜓; see natded 27260. This is Definition NNC in [Pfenning] p. 17. This rule is valid in classical logic (our logic), but not in intuitionistic logic. (Contributed by DAW, 8-Feb-2017.) |
Ref | Expression |
---|---|
notnotrd.1 | ⊢ (𝜑 → ¬ ¬ 𝜓) |
Ref | Expression |
---|---|
notnotrd | ⊢ (𝜑 → 𝜓) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | notnotrd.1 | . 2 ⊢ (𝜑 → ¬ ¬ 𝜓) | |
2 | notnotr 125 | . 2 ⊢ (¬ ¬ 𝜓 → 𝜓) | |
3 | 1, 2 | syl 17 | 1 ⊢ (𝜑 → 𝜓) |
Colors of variables: wff setvar class |
Syntax hints: ¬ wn 3 → wi 4 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 |
This theorem is referenced by: condan 835 efald 1504 necon1ai 2821 supgtoreq 8376 konigthlem 9390 indpi 9729 sqrmo 13992 axtgupdim2 25370 ncoltgdim2 25460 ex-natded5.13 27272 2sqcoprm 29647 bnj1204 31080 knoppndvlem10 32512 supxrgere 39549 supxrgelem 39553 supxrge 39554 iccdifprioo 39742 icccncfext 40100 stirlinglem5 40295 sge0repnf 40603 sge0split 40626 nnfoctbdjlem 40672 nabctnabc 41098 |
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