Mathbox for Thierry Arnoux |
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Mirrors > Home > MPE Home > Th. List > Mathboxes > sgnnbi | Structured version Visualization version GIF version |
Description: Negative signum. (Contributed by Thierry Arnoux, 2-Oct-2018.) |
Ref | Expression |
---|---|
sgnnbi | ⊢ (𝐴 ∈ ℝ* → ((sgn‘𝐴) = -1 ↔ 𝐴 < 0)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | id 22 | . . . 4 ⊢ (𝐴 ∈ ℝ* → 𝐴 ∈ ℝ*) | |
2 | eqeq1 2825 | . . . . 5 ⊢ ((sgn‘𝐴) = 0 → ((sgn‘𝐴) = -1 ↔ 0 = -1)) | |
3 | 2 | imbi1d 344 | . . . 4 ⊢ ((sgn‘𝐴) = 0 → (((sgn‘𝐴) = -1 → 𝐴 < 0) ↔ (0 = -1 → 𝐴 < 0))) |
4 | eqeq1 2825 | . . . . 5 ⊢ ((sgn‘𝐴) = 1 → ((sgn‘𝐴) = -1 ↔ 1 = -1)) | |
5 | 4 | imbi1d 344 | . . . 4 ⊢ ((sgn‘𝐴) = 1 → (((sgn‘𝐴) = -1 → 𝐴 < 0) ↔ (1 = -1 → 𝐴 < 0))) |
6 | eqeq1 2825 | . . . . 5 ⊢ ((sgn‘𝐴) = -1 → ((sgn‘𝐴) = -1 ↔ -1 = -1)) | |
7 | 6 | imbi1d 344 | . . . 4 ⊢ ((sgn‘𝐴) = -1 → (((sgn‘𝐴) = -1 → 𝐴 < 0) ↔ (-1 = -1 → 𝐴 < 0))) |
8 | neg1ne0 11754 | . . . . . . 7 ⊢ -1 ≠ 0 | |
9 | 8 | nesymi 3073 | . . . . . 6 ⊢ ¬ 0 = -1 |
10 | 9 | pm2.21i 119 | . . . . 5 ⊢ (0 = -1 → 𝐴 < 0) |
11 | 10 | a1i 11 | . . . 4 ⊢ ((𝐴 ∈ ℝ* ∧ 𝐴 = 0) → (0 = -1 → 𝐴 < 0)) |
12 | neg1rr 11753 | . . . . . . . 8 ⊢ -1 ∈ ℝ | |
13 | neg1lt0 11755 | . . . . . . . . 9 ⊢ -1 < 0 | |
14 | 0lt1 11162 | . . . . . . . . 9 ⊢ 0 < 1 | |
15 | 0re 10643 | . . . . . . . . . 10 ⊢ 0 ∈ ℝ | |
16 | 1re 10641 | . . . . . . . . . 10 ⊢ 1 ∈ ℝ | |
17 | 12, 15, 16 | lttri 10766 | . . . . . . . . 9 ⊢ ((-1 < 0 ∧ 0 < 1) → -1 < 1) |
18 | 13, 14, 17 | mp2an 690 | . . . . . . . 8 ⊢ -1 < 1 |
19 | 12, 18 | gtneii 10752 | . . . . . . 7 ⊢ 1 ≠ -1 |
20 | 19 | neii 3018 | . . . . . 6 ⊢ ¬ 1 = -1 |
21 | 20 | pm2.21i 119 | . . . . 5 ⊢ (1 = -1 → 𝐴 < 0) |
22 | 21 | a1i 11 | . . . 4 ⊢ ((𝐴 ∈ ℝ* ∧ 0 < 𝐴) → (1 = -1 → 𝐴 < 0)) |
23 | simp2 1133 | . . . . 5 ⊢ ((𝐴 ∈ ℝ* ∧ 𝐴 < 0 ∧ -1 = -1) → 𝐴 < 0) | |
24 | 23 | 3expia 1117 | . . . 4 ⊢ ((𝐴 ∈ ℝ* ∧ 𝐴 < 0) → (-1 = -1 → 𝐴 < 0)) |
25 | 1, 3, 5, 7, 11, 22, 24 | sgn3da 31799 | . . 3 ⊢ (𝐴 ∈ ℝ* → ((sgn‘𝐴) = -1 → 𝐴 < 0)) |
26 | 25 | imp 409 | . 2 ⊢ ((𝐴 ∈ ℝ* ∧ (sgn‘𝐴) = -1) → 𝐴 < 0) |
27 | sgnn 14453 | . 2 ⊢ ((𝐴 ∈ ℝ* ∧ 𝐴 < 0) → (sgn‘𝐴) = -1) | |
28 | 26, 27 | impbida 799 | 1 ⊢ (𝐴 ∈ ℝ* → ((sgn‘𝐴) = -1 ↔ 𝐴 < 0)) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 208 ∧ wa 398 = wceq 1537 ∈ wcel 2114 class class class wbr 5066 ‘cfv 6355 0cc0 10537 1c1 10538 ℝ*cxr 10674 < clt 10675 -cneg 10871 sgncsgn 14445 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1796 ax-4 1810 ax-5 1911 ax-6 1970 ax-7 2015 ax-8 2116 ax-9 2124 ax-10 2145 ax-11 2161 ax-12 2177 ax-ext 2793 ax-sep 5203 ax-nul 5210 ax-pow 5266 ax-pr 5330 ax-un 7461 ax-cnex 10593 ax-resscn 10594 ax-1cn 10595 ax-icn 10596 ax-addcl 10597 ax-addrcl 10598 ax-mulcl 10599 ax-mulrcl 10600 ax-mulcom 10601 ax-addass 10602 ax-mulass 10603 ax-distr 10604 ax-i2m1 10605 ax-1ne0 10606 ax-1rid 10607 ax-rnegex 10608 ax-rrecex 10609 ax-cnre 10610 ax-pre-lttri 10611 ax-pre-lttrn 10612 ax-pre-ltadd 10613 ax-pre-mulgt0 10614 |
This theorem depends on definitions: df-bi 209 df-an 399 df-or 844 df-3or 1084 df-3an 1085 df-tru 1540 df-ex 1781 df-nf 1785 df-sb 2070 df-mo 2622 df-eu 2654 df-clab 2800 df-cleq 2814 df-clel 2893 df-nfc 2963 df-ne 3017 df-nel 3124 df-ral 3143 df-rex 3144 df-reu 3145 df-rab 3147 df-v 3496 df-sbc 3773 df-csb 3884 df-dif 3939 df-un 3941 df-in 3943 df-ss 3952 df-nul 4292 df-if 4468 df-pw 4541 df-sn 4568 df-pr 4570 df-op 4574 df-uni 4839 df-br 5067 df-opab 5129 df-mpt 5147 df-id 5460 df-po 5474 df-so 5475 df-xp 5561 df-rel 5562 df-cnv 5563 df-co 5564 df-dm 5565 df-rn 5566 df-res 5567 df-ima 5568 df-iota 6314 df-fun 6357 df-fn 6358 df-f 6359 df-f1 6360 df-fo 6361 df-f1o 6362 df-fv 6363 df-riota 7114 df-ov 7159 df-oprab 7160 df-mpo 7161 df-er 8289 df-en 8510 df-dom 8511 df-sdom 8512 df-pnf 10677 df-mnf 10678 df-xr 10679 df-ltxr 10680 df-le 10681 df-sub 10872 df-neg 10873 df-sgn 14446 |
This theorem is referenced by: sgnmulsgn 31807 |
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