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Mirrors > Home > MPE Home > Th. List > notnotrd | Structured version Visualization version GIF version |
Description: Deduction associated with notnotr 132 and notnotri 133. Double negation elimination rule. A translation of the natural deduction rule ¬ ¬ C , Γ⊢ ¬ ¬ 𝜓 ⇒ Γ⊢ 𝜓; see natded 28174. 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 132 | . 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 816 efald 1552 necon1ai 3041 supgtoreq 8926 konigthlem 9982 indpi 10321 sqrmo 14603 2sqcoprm 26003 axtgupdim2 26249 ncoltgdim2 26343 ex-natded5.13 28186 bnj1204 32277 knoppndvlem10 33853 supxrgere 41591 supxrgelem 41595 supxrge 41596 iccdifprioo 41782 icccncfext 42160 stirlinglem5 42354 sge0repnf 42659 sge0split 42682 nnfoctbdjlem 42728 nabctnabc 43158 |
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