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Mirrors > Home > MPE Home > Th. List > sgnpnf | Structured version Visualization version GIF version |
Description: The signum of +∞ is 1. (Contributed by David A. Wheeler, 26-Jun-2016.) |
Ref | Expression |
---|---|
sgnpnf | ⊢ (sgn‘+∞) = 1 |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | pnfxr 10430 | . 2 ⊢ +∞ ∈ ℝ* | |
2 | 0ltpnf 12267 | . 2 ⊢ 0 < +∞ | |
3 | sgnp 14237 | . 2 ⊢ ((+∞ ∈ ℝ* ∧ 0 < +∞) → (sgn‘+∞) = 1) | |
4 | 1, 2, 3 | mp2an 682 | 1 ⊢ (sgn‘+∞) = 1 |
Colors of variables: wff setvar class |
Syntax hints: = wceq 1601 ∈ wcel 2106 class class class wbr 4886 ‘cfv 6135 0cc0 10272 1c1 10273 +∞cpnf 10408 ℝ*cxr 10410 < clt 10411 sgncsgn 14233 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1839 ax-4 1853 ax-5 1953 ax-6 2021 ax-7 2054 ax-8 2108 ax-9 2115 ax-10 2134 ax-11 2149 ax-12 2162 ax-13 2333 ax-ext 2753 ax-sep 5017 ax-nul 5025 ax-pow 5077 ax-pr 5138 ax-un 7226 ax-cnex 10328 ax-resscn 10329 ax-1cn 10330 ax-icn 10331 ax-addcl 10332 ax-addrcl 10333 ax-mulcl 10334 ax-i2m1 10340 ax-rnegex 10343 ax-cnre 10345 ax-pre-lttri 10346 ax-pre-lttrn 10347 |
This theorem depends on definitions: df-bi 199 df-an 387 df-or 837 df-3or 1072 df-3an 1073 df-tru 1605 df-ex 1824 df-nf 1828 df-sb 2012 df-mo 2550 df-eu 2586 df-clab 2763 df-cleq 2769 df-clel 2773 df-nfc 2920 df-ne 2969 df-nel 3075 df-ral 3094 df-rex 3095 df-rab 3098 df-v 3399 df-sbc 3652 df-csb 3751 df-dif 3794 df-un 3796 df-in 3798 df-ss 3805 df-nul 4141 df-if 4307 df-pw 4380 df-sn 4398 df-pr 4400 df-op 4404 df-uni 4672 df-br 4887 df-opab 4949 df-mpt 4966 df-id 5261 df-po 5274 df-so 5275 df-xp 5361 df-rel 5362 df-cnv 5363 df-co 5364 df-dm 5365 df-rn 5366 df-res 5367 df-ima 5368 df-iota 6099 df-fun 6137 df-fn 6138 df-f 6139 df-f1 6140 df-fo 6141 df-f1o 6142 df-fv 6143 df-ov 6925 df-er 8026 df-en 8242 df-dom 8243 df-sdom 8244 df-pnf 10413 df-mnf 10414 df-xr 10415 df-ltxr 10416 df-neg 10609 df-sgn 14234 |
This theorem is referenced by: (None) |
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