![]() |
Metamath Proof Explorer |
< Previous
Next >
Nearby theorems |
|
Mirrors > Home > MPE Home > Th. List > sgn0 | Structured version Visualization version GIF version |
Description: The signum of 0 is 0. (Contributed by David A. Wheeler, 15-May-2015.) |
Ref | Expression |
---|---|
sgn0 | ⊢ (sgn‘0) = 0 |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | 0xr 11259 | . . 3 ⊢ 0 ∈ ℝ* | |
2 | sgnval 15033 | . . 3 ⊢ (0 ∈ ℝ* → (sgn‘0) = if(0 = 0, 0, if(0 < 0, -1, 1))) | |
3 | 1, 2 | ax-mp 5 | . 2 ⊢ (sgn‘0) = if(0 = 0, 0, if(0 < 0, -1, 1)) |
4 | eqid 2724 | . . 3 ⊢ 0 = 0 | |
5 | 4 | iftruei 4528 | . 2 ⊢ if(0 = 0, 0, if(0 < 0, -1, 1)) = 0 |
6 | 3, 5 | eqtri 2752 | 1 ⊢ (sgn‘0) = 0 |
Colors of variables: wff setvar class |
Syntax hints: = wceq 1533 ∈ wcel 2098 ifcif 4521 class class class wbr 5139 ‘cfv 6534 0cc0 11107 1c1 11108 ℝ*cxr 11245 < clt 11246 -cneg 11443 sgncsgn 15031 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1789 ax-4 1803 ax-5 1905 ax-6 1963 ax-7 2003 ax-8 2100 ax-9 2108 ax-10 2129 ax-11 2146 ax-12 2163 ax-ext 2695 ax-sep 5290 ax-nul 5297 ax-pr 5418 ax-1cn 11165 ax-icn 11166 ax-addcl 11167 ax-addrcl 11168 ax-mulcl 11169 ax-i2m1 11175 ax-rnegex 11178 ax-cnre 11180 |
This theorem depends on definitions: df-bi 206 df-an 396 df-or 845 df-3an 1086 df-tru 1536 df-fal 1546 df-ex 1774 df-nf 1778 df-sb 2060 df-mo 2526 df-eu 2555 df-clab 2702 df-cleq 2716 df-clel 2802 df-nfc 2877 df-ne 2933 df-ral 3054 df-rex 3063 df-rab 3425 df-v 3468 df-dif 3944 df-un 3946 df-in 3948 df-ss 3958 df-nul 4316 df-if 4522 df-sn 4622 df-pr 4624 df-op 4628 df-uni 4901 df-br 5140 df-opab 5202 df-mpt 5223 df-id 5565 df-xp 5673 df-rel 5674 df-cnv 5675 df-co 5676 df-dm 5677 df-iota 6486 df-fun 6536 df-fv 6542 df-ov 7405 df-xr 11250 df-neg 11445 df-sgn 15032 |
This theorem is referenced by: sgncl 34029 sgnmul 34033 sgnsgn 34039 signstfveq0 34080 |
Copyright terms: Public domain | W3C validator |