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Theorem sgnsval 32823
Description: The sign value. (Contributed by Thierry Arnoux, 9-Sep-2018.)
Hypotheses
Ref Expression
sgnsval.b 𝐵 = (Base‘𝑅)
sgnsval.0 0 = (0g𝑅)
sgnsval.l < = (lt‘𝑅)
sgnsval.s 𝑆 = (sgns𝑅)
Assertion
Ref Expression
sgnsval ((𝑅𝑉𝑋𝐵) → (𝑆𝑋) = if(𝑋 = 0 , 0, if( 0 < 𝑋, 1, -1)))

Proof of Theorem sgnsval
Dummy variable 𝑥 is distinct from all other variables.
StepHypRef Expression
1 sgnsval.b . . . 4 𝐵 = (Base‘𝑅)
2 sgnsval.0 . . . 4 0 = (0g𝑅)
3 sgnsval.l . . . 4 < = (lt‘𝑅)
4 sgnsval.s . . . 4 𝑆 = (sgns𝑅)
51, 2, 3, 4sgnsv 32822 . . 3 (𝑅𝑉𝑆 = (𝑥𝐵 ↦ if(𝑥 = 0 , 0, if( 0 < 𝑥, 1, -1))))
65adantr 480 . 2 ((𝑅𝑉𝑋𝐵) → 𝑆 = (𝑥𝐵 ↦ if(𝑥 = 0 , 0, if( 0 < 𝑥, 1, -1))))
7 eqeq1 2730 . . . 4 (𝑥 = 𝑋 → (𝑥 = 0𝑋 = 0 ))
8 breq2 5145 . . . . 5 (𝑥 = 𝑋 → ( 0 < 𝑥0 < 𝑋))
98ifbid 4546 . . . 4 (𝑥 = 𝑋 → if( 0 < 𝑥, 1, -1) = if( 0 < 𝑋, 1, -1))
107, 9ifbieq2d 4549 . . 3 (𝑥 = 𝑋 → if(𝑥 = 0 , 0, if( 0 < 𝑥, 1, -1)) = if(𝑋 = 0 , 0, if( 0 < 𝑋, 1, -1)))
1110adantl 481 . 2 (((𝑅𝑉𝑋𝐵) ∧ 𝑥 = 𝑋) → if(𝑥 = 0 , 0, if( 0 < 𝑥, 1, -1)) = if(𝑋 = 0 , 0, if( 0 < 𝑋, 1, -1)))
12 simpr 484 . 2 ((𝑅𝑉𝑋𝐵) → 𝑋𝐵)
13 c0ex 11209 . . . 4 0 ∈ V
1413a1i 11 . . 3 (((𝑅𝑉𝑋𝐵) ∧ 𝑋 = 0 ) → 0 ∈ V)
15 1ex 11211 . . . . 5 1 ∈ V
1615a1i 11 . . . 4 ((((𝑅𝑉𝑋𝐵) ∧ ¬ 𝑋 = 0 ) ∧ 0 < 𝑋) → 1 ∈ V)
17 negex 11459 . . . . 5 -1 ∈ V
1817a1i 11 . . . 4 ((((𝑅𝑉𝑋𝐵) ∧ ¬ 𝑋 = 0 ) ∧ ¬ 0 < 𝑋) → -1 ∈ V)
1916, 18ifclda 4558 . . 3 (((𝑅𝑉𝑋𝐵) ∧ ¬ 𝑋 = 0 ) → if( 0 < 𝑋, 1, -1) ∈ V)
2014, 19ifclda 4558 . 2 ((𝑅𝑉𝑋𝐵) → if(𝑋 = 0 , 0, if( 0 < 𝑋, 1, -1)) ∈ V)
216, 11, 12, 20fvmptd 6998 1 ((𝑅𝑉𝑋𝐵) → (𝑆𝑋) = if(𝑋 = 0 , 0, if( 0 < 𝑋, 1, -1)))
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wi 4  wa 395   = wceq 1533  wcel 2098  Vcvv 3468  ifcif 4523   class class class wbr 5141  cmpt 5224  cfv 6536  0cc0 11109  1c1 11110  -cneg 11446  Basecbs 17150  0gc0g 17391  ltcplt 18270  sgnscsgns 32820
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 2697  ax-rep 5278  ax-sep 5292  ax-nul 5299  ax-pr 5420  ax-1cn 11167  ax-icn 11168  ax-addcl 11169  ax-mulcl 11171  ax-i2m1 11177
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 2528  df-eu 2557  df-clab 2704  df-cleq 2718  df-clel 2804  df-nfc 2879  df-ne 2935  df-ral 3056  df-rex 3065  df-reu 3371  df-rab 3427  df-v 3470  df-sbc 3773  df-csb 3889  df-dif 3946  df-un 3948  df-in 3950  df-ss 3960  df-nul 4318  df-if 4524  df-sn 4624  df-pr 4626  df-op 4630  df-uni 4903  df-iun 4992  df-br 5142  df-opab 5204  df-mpt 5225  df-id 5567  df-xp 5675  df-rel 5676  df-cnv 5677  df-co 5678  df-dm 5679  df-rn 5680  df-res 5681  df-ima 5682  df-iota 6488  df-fun 6538  df-fn 6539  df-f 6540  df-f1 6541  df-fo 6542  df-f1o 6543  df-fv 6544  df-ov 7407  df-neg 11448  df-sgns 32821
This theorem is referenced by: (None)
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