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Theorem xmulval 11930
Description: Value of the extended real multiplication operation. (Contributed by Mario Carneiro, 20-Aug-2015.)
Assertion
Ref Expression
xmulval ((𝐴 ∈ ℝ*𝐵 ∈ ℝ*) → (𝐴 ·e 𝐵) = if((𝐴 = 0 ∨ 𝐵 = 0), 0, if((((0 < 𝐵𝐴 = +∞) ∨ (𝐵 < 0 ∧ 𝐴 = -∞)) ∨ ((0 < 𝐴𝐵 = +∞) ∨ (𝐴 < 0 ∧ 𝐵 = -∞))), +∞, if((((0 < 𝐵𝐴 = -∞) ∨ (𝐵 < 0 ∧ 𝐴 = +∞)) ∨ ((0 < 𝐴𝐵 = -∞) ∨ (𝐴 < 0 ∧ 𝐵 = +∞))), -∞, (𝐴 · 𝐵)))))

Proof of Theorem xmulval
Dummy variables 𝑥 𝑦 are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 simpl 472 . . . . 5 ((𝑥 = 𝐴𝑦 = 𝐵) → 𝑥 = 𝐴)
21eqeq1d 2612 . . . 4 ((𝑥 = 𝐴𝑦 = 𝐵) → (𝑥 = 0 ↔ 𝐴 = 0))
3 simpr 476 . . . . 5 ((𝑥 = 𝐴𝑦 = 𝐵) → 𝑦 = 𝐵)
43eqeq1d 2612 . . . 4 ((𝑥 = 𝐴𝑦 = 𝐵) → (𝑦 = 0 ↔ 𝐵 = 0))
52, 4orbi12d 742 . . 3 ((𝑥 = 𝐴𝑦 = 𝐵) → ((𝑥 = 0 ∨ 𝑦 = 0) ↔ (𝐴 = 0 ∨ 𝐵 = 0)))
63breq2d 4595 . . . . . . 7 ((𝑥 = 𝐴𝑦 = 𝐵) → (0 < 𝑦 ↔ 0 < 𝐵))
71eqeq1d 2612 . . . . . . 7 ((𝑥 = 𝐴𝑦 = 𝐵) → (𝑥 = +∞ ↔ 𝐴 = +∞))
86, 7anbi12d 743 . . . . . 6 ((𝑥 = 𝐴𝑦 = 𝐵) → ((0 < 𝑦𝑥 = +∞) ↔ (0 < 𝐵𝐴 = +∞)))
93breq1d 4593 . . . . . . 7 ((𝑥 = 𝐴𝑦 = 𝐵) → (𝑦 < 0 ↔ 𝐵 < 0))
101eqeq1d 2612 . . . . . . 7 ((𝑥 = 𝐴𝑦 = 𝐵) → (𝑥 = -∞ ↔ 𝐴 = -∞))
119, 10anbi12d 743 . . . . . 6 ((𝑥 = 𝐴𝑦 = 𝐵) → ((𝑦 < 0 ∧ 𝑥 = -∞) ↔ (𝐵 < 0 ∧ 𝐴 = -∞)))
128, 11orbi12d 742 . . . . 5 ((𝑥 = 𝐴𝑦 = 𝐵) → (((0 < 𝑦𝑥 = +∞) ∨ (𝑦 < 0 ∧ 𝑥 = -∞)) ↔ ((0 < 𝐵𝐴 = +∞) ∨ (𝐵 < 0 ∧ 𝐴 = -∞))))
131breq2d 4595 . . . . . . 7 ((𝑥 = 𝐴𝑦 = 𝐵) → (0 < 𝑥 ↔ 0 < 𝐴))
143eqeq1d 2612 . . . . . . 7 ((𝑥 = 𝐴𝑦 = 𝐵) → (𝑦 = +∞ ↔ 𝐵 = +∞))
1513, 14anbi12d 743 . . . . . 6 ((𝑥 = 𝐴𝑦 = 𝐵) → ((0 < 𝑥𝑦 = +∞) ↔ (0 < 𝐴𝐵 = +∞)))
161breq1d 4593 . . . . . . 7 ((𝑥 = 𝐴𝑦 = 𝐵) → (𝑥 < 0 ↔ 𝐴 < 0))
173eqeq1d 2612 . . . . . . 7 ((𝑥 = 𝐴𝑦 = 𝐵) → (𝑦 = -∞ ↔ 𝐵 = -∞))
1816, 17anbi12d 743 . . . . . 6 ((𝑥 = 𝐴𝑦 = 𝐵) → ((𝑥 < 0 ∧ 𝑦 = -∞) ↔ (𝐴 < 0 ∧ 𝐵 = -∞)))
1915, 18orbi12d 742 . . . . 5 ((𝑥 = 𝐴𝑦 = 𝐵) → (((0 < 𝑥𝑦 = +∞) ∨ (𝑥 < 0 ∧ 𝑦 = -∞)) ↔ ((0 < 𝐴𝐵 = +∞) ∨ (𝐴 < 0 ∧ 𝐵 = -∞))))
2012, 19orbi12d 742 . . . 4 ((𝑥 = 𝐴𝑦 = 𝐵) → ((((0 < 𝑦𝑥 = +∞) ∨ (𝑦 < 0 ∧ 𝑥 = -∞)) ∨ ((0 < 𝑥𝑦 = +∞) ∨ (𝑥 < 0 ∧ 𝑦 = -∞))) ↔ (((0 < 𝐵𝐴 = +∞) ∨ (𝐵 < 0 ∧ 𝐴 = -∞)) ∨ ((0 < 𝐴𝐵 = +∞) ∨ (𝐴 < 0 ∧ 𝐵 = -∞)))))
216, 10anbi12d 743 . . . . . . 7 ((𝑥 = 𝐴𝑦 = 𝐵) → ((0 < 𝑦𝑥 = -∞) ↔ (0 < 𝐵𝐴 = -∞)))
229, 7anbi12d 743 . . . . . . 7 ((𝑥 = 𝐴𝑦 = 𝐵) → ((𝑦 < 0 ∧ 𝑥 = +∞) ↔ (𝐵 < 0 ∧ 𝐴 = +∞)))
2321, 22orbi12d 742 . . . . . 6 ((𝑥 = 𝐴𝑦 = 𝐵) → (((0 < 𝑦𝑥 = -∞) ∨ (𝑦 < 0 ∧ 𝑥 = +∞)) ↔ ((0 < 𝐵𝐴 = -∞) ∨ (𝐵 < 0 ∧ 𝐴 = +∞))))
2413, 17anbi12d 743 . . . . . . 7 ((𝑥 = 𝐴𝑦 = 𝐵) → ((0 < 𝑥𝑦 = -∞) ↔ (0 < 𝐴𝐵 = -∞)))
2516, 14anbi12d 743 . . . . . . 7 ((𝑥 = 𝐴𝑦 = 𝐵) → ((𝑥 < 0 ∧ 𝑦 = +∞) ↔ (𝐴 < 0 ∧ 𝐵 = +∞)))
2624, 25orbi12d 742 . . . . . 6 ((𝑥 = 𝐴𝑦 = 𝐵) → (((0 < 𝑥𝑦 = -∞) ∨ (𝑥 < 0 ∧ 𝑦 = +∞)) ↔ ((0 < 𝐴𝐵 = -∞) ∨ (𝐴 < 0 ∧ 𝐵 = +∞))))
2723, 26orbi12d 742 . . . . 5 ((𝑥 = 𝐴𝑦 = 𝐵) → ((((0 < 𝑦𝑥 = -∞) ∨ (𝑦 < 0 ∧ 𝑥 = +∞)) ∨ ((0 < 𝑥𝑦 = -∞) ∨ (𝑥 < 0 ∧ 𝑦 = +∞))) ↔ (((0 < 𝐵𝐴 = -∞) ∨ (𝐵 < 0 ∧ 𝐴 = +∞)) ∨ ((0 < 𝐴𝐵 = -∞) ∨ (𝐴 < 0 ∧ 𝐵 = +∞)))))
28 oveq12 6558 . . . . 5 ((𝑥 = 𝐴𝑦 = 𝐵) → (𝑥 · 𝑦) = (𝐴 · 𝐵))
2927, 28ifbieq2d 4061 . . . 4 ((𝑥 = 𝐴𝑦 = 𝐵) → if((((0 < 𝑦𝑥 = -∞) ∨ (𝑦 < 0 ∧ 𝑥 = +∞)) ∨ ((0 < 𝑥𝑦 = -∞) ∨ (𝑥 < 0 ∧ 𝑦 = +∞))), -∞, (𝑥 · 𝑦)) = if((((0 < 𝐵𝐴 = -∞) ∨ (𝐵 < 0 ∧ 𝐴 = +∞)) ∨ ((0 < 𝐴𝐵 = -∞) ∨ (𝐴 < 0 ∧ 𝐵 = +∞))), -∞, (𝐴 · 𝐵)))
3020, 29ifbieq2d 4061 . . 3 ((𝑥 = 𝐴𝑦 = 𝐵) → if((((0 < 𝑦𝑥 = +∞) ∨ (𝑦 < 0 ∧ 𝑥 = -∞)) ∨ ((0 < 𝑥𝑦 = +∞) ∨ (𝑥 < 0 ∧ 𝑦 = -∞))), +∞, if((((0 < 𝑦𝑥 = -∞) ∨ (𝑦 < 0 ∧ 𝑥 = +∞)) ∨ ((0 < 𝑥𝑦 = -∞) ∨ (𝑥 < 0 ∧ 𝑦 = +∞))), -∞, (𝑥 · 𝑦))) = if((((0 < 𝐵𝐴 = +∞) ∨ (𝐵 < 0 ∧ 𝐴 = -∞)) ∨ ((0 < 𝐴𝐵 = +∞) ∨ (𝐴 < 0 ∧ 𝐵 = -∞))), +∞, if((((0 < 𝐵𝐴 = -∞) ∨ (𝐵 < 0 ∧ 𝐴 = +∞)) ∨ ((0 < 𝐴𝐵 = -∞) ∨ (𝐴 < 0 ∧ 𝐵 = +∞))), -∞, (𝐴 · 𝐵))))
315, 30ifbieq2d 4061 . 2 ((𝑥 = 𝐴𝑦 = 𝐵) → if((𝑥 = 0 ∨ 𝑦 = 0), 0, if((((0 < 𝑦𝑥 = +∞) ∨ (𝑦 < 0 ∧ 𝑥 = -∞)) ∨ ((0 < 𝑥𝑦 = +∞) ∨ (𝑥 < 0 ∧ 𝑦 = -∞))), +∞, if((((0 < 𝑦𝑥 = -∞) ∨ (𝑦 < 0 ∧ 𝑥 = +∞)) ∨ ((0 < 𝑥𝑦 = -∞) ∨ (𝑥 < 0 ∧ 𝑦 = +∞))), -∞, (𝑥 · 𝑦)))) = if((𝐴 = 0 ∨ 𝐵 = 0), 0, if((((0 < 𝐵𝐴 = +∞) ∨ (𝐵 < 0 ∧ 𝐴 = -∞)) ∨ ((0 < 𝐴𝐵 = +∞) ∨ (𝐴 < 0 ∧ 𝐵 = -∞))), +∞, if((((0 < 𝐵𝐴 = -∞) ∨ (𝐵 < 0 ∧ 𝐴 = +∞)) ∨ ((0 < 𝐴𝐵 = -∞) ∨ (𝐴 < 0 ∧ 𝐵 = +∞))), -∞, (𝐴 · 𝐵)))))
32 df-xmul 11824 . 2 ·e = (𝑥 ∈ ℝ*, 𝑦 ∈ ℝ* ↦ if((𝑥 = 0 ∨ 𝑦 = 0), 0, if((((0 < 𝑦𝑥 = +∞) ∨ (𝑦 < 0 ∧ 𝑥 = -∞)) ∨ ((0 < 𝑥𝑦 = +∞) ∨ (𝑥 < 0 ∧ 𝑦 = -∞))), +∞, if((((0 < 𝑦𝑥 = -∞) ∨ (𝑦 < 0 ∧ 𝑥 = +∞)) ∨ ((0 < 𝑥𝑦 = -∞) ∨ (𝑥 < 0 ∧ 𝑦 = +∞))), -∞, (𝑥 · 𝑦)))))
33 c0ex 9913 . . 3 0 ∈ V
34 pnfex 9972 . . . 4 +∞ ∈ V
35 mnfxr 9975 . . . . . 6 -∞ ∈ ℝ*
3635elexi 3186 . . . . 5 -∞ ∈ V
37 ovex 6577 . . . . 5 (𝐴 · 𝐵) ∈ V
3836, 37ifex 4106 . . . 4 if((((0 < 𝐵𝐴 = -∞) ∨ (𝐵 < 0 ∧ 𝐴 = +∞)) ∨ ((0 < 𝐴𝐵 = -∞) ∨ (𝐴 < 0 ∧ 𝐵 = +∞))), -∞, (𝐴 · 𝐵)) ∈ V
3934, 38ifex 4106 . . 3 if((((0 < 𝐵𝐴 = +∞) ∨ (𝐵 < 0 ∧ 𝐴 = -∞)) ∨ ((0 < 𝐴𝐵 = +∞) ∨ (𝐴 < 0 ∧ 𝐵 = -∞))), +∞, if((((0 < 𝐵𝐴 = -∞) ∨ (𝐵 < 0 ∧ 𝐴 = +∞)) ∨ ((0 < 𝐴𝐵 = -∞) ∨ (𝐴 < 0 ∧ 𝐵 = +∞))), -∞, (𝐴 · 𝐵))) ∈ V
4033, 39ifex 4106 . 2 if((𝐴 = 0 ∨ 𝐵 = 0), 0, if((((0 < 𝐵𝐴 = +∞) ∨ (𝐵 < 0 ∧ 𝐴 = -∞)) ∨ ((0 < 𝐴𝐵 = +∞) ∨ (𝐴 < 0 ∧ 𝐵 = -∞))), +∞, if((((0 < 𝐵𝐴 = -∞) ∨ (𝐵 < 0 ∧ 𝐴 = +∞)) ∨ ((0 < 𝐴𝐵 = -∞) ∨ (𝐴 < 0 ∧ 𝐵 = +∞))), -∞, (𝐴 · 𝐵)))) ∈ V
4131, 32, 40ovmpt2a 6689 1 ((𝐴 ∈ ℝ*𝐵 ∈ ℝ*) → (𝐴 ·e 𝐵) = if((𝐴 = 0 ∨ 𝐵 = 0), 0, if((((0 < 𝐵𝐴 = +∞) ∨ (𝐵 < 0 ∧ 𝐴 = -∞)) ∨ ((0 < 𝐴𝐵 = +∞) ∨ (𝐴 < 0 ∧ 𝐵 = -∞))), +∞, if((((0 < 𝐵𝐴 = -∞) ∨ (𝐵 < 0 ∧ 𝐴 = +∞)) ∨ ((0 < 𝐴𝐵 = -∞) ∨ (𝐴 < 0 ∧ 𝐵 = +∞))), -∞, (𝐴 · 𝐵)))))
Colors of variables: wff setvar class
Syntax hints:  wi 4  wo 382  wa 383   = wceq 1475  wcel 1977  ifcif 4036   class class class wbr 4583  (class class class)co 6549  0cc0 9815   · cmul 9820  +∞cpnf 9950  -∞cmnf 9951  *cxr 9952   < clt 9953   ·e cxmu 11821
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1713  ax-4 1728  ax-5 1827  ax-6 1875  ax-7 1922  ax-8 1979  ax-9 1986  ax-10 2006  ax-11 2021  ax-12 2034  ax-13 2234  ax-ext 2590  ax-sep 4709  ax-nul 4717  ax-pow 4769  ax-pr 4833  ax-un 6847  ax-cnex 9871  ax-1cn 9873  ax-icn 9874  ax-addcl 9875  ax-mulcl 9877  ax-i2m1 9883
This theorem depends on definitions:  df-bi 196  df-or 384  df-an 385  df-3an 1033  df-tru 1478  df-ex 1696  df-nf 1701  df-sb 1868  df-eu 2462  df-mo 2463  df-clab 2597  df-cleq 2603  df-clel 2606  df-nfc 2740  df-ral 2901  df-rex 2902  df-rab 2905  df-v 3175  df-sbc 3403  df-dif 3543  df-un 3545  df-in 3547  df-ss 3554  df-nul 3875  df-if 4037  df-pw 4110  df-sn 4126  df-pr 4128  df-op 4132  df-uni 4373  df-br 4584  df-opab 4644  df-id 4953  df-xp 5044  df-rel 5045  df-cnv 5046  df-co 5047  df-dm 5048  df-iota 5768  df-fun 5806  df-fv 5812  df-ov 6552  df-oprab 6553  df-mpt2 6554  df-pnf 9955  df-mnf 9956  df-xr 9957  df-xmul 11824
This theorem is referenced by:  xmulcom  11968  xmul01  11969  xmulneg1  11971  rexmul  11973  xmulpnf1  11976
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