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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 2732 | . . . . 5 ⊢ ((sgn‘𝐴) = 0 → ((sgn‘𝐴) = -1 ↔ 0 = -1)) | |
3 | 2 | imbi1d 341 | . . . 4 ⊢ ((sgn‘𝐴) = 0 → (((sgn‘𝐴) = -1 → 𝐴 < 0) ↔ (0 = -1 → 𝐴 < 0))) |
4 | eqeq1 2732 | . . . . 5 ⊢ ((sgn‘𝐴) = 1 → ((sgn‘𝐴) = -1 ↔ 1 = -1)) | |
5 | 4 | imbi1d 341 | . . . 4 ⊢ ((sgn‘𝐴) = 1 → (((sgn‘𝐴) = -1 → 𝐴 < 0) ↔ (1 = -1 → 𝐴 < 0))) |
6 | eqeq1 2732 | . . . . 5 ⊢ ((sgn‘𝐴) = -1 → ((sgn‘𝐴) = -1 ↔ -1 = -1)) | |
7 | 6 | imbi1d 341 | . . . 4 ⊢ ((sgn‘𝐴) = -1 → (((sgn‘𝐴) = -1 → 𝐴 < 0) ↔ (-1 = -1 → 𝐴 < 0))) |
8 | neg1ne0 12359 | . . . . . . 7 ⊢ -1 ≠ 0 | |
9 | 8 | nesymi 2995 | . . . . . 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 12358 | . . . . . . . 8 ⊢ -1 ∈ ℝ | |
13 | neg1lt0 12360 | . . . . . . . . 9 ⊢ -1 < 0 | |
14 | 0lt1 11767 | . . . . . . . . 9 ⊢ 0 < 1 | |
15 | 0re 11247 | . . . . . . . . . 10 ⊢ 0 ∈ ℝ | |
16 | 1re 11245 | . . . . . . . . . 10 ⊢ 1 ∈ ℝ | |
17 | 12, 15, 16 | lttri 11371 | . . . . . . . . 9 ⊢ ((-1 < 0 ∧ 0 < 1) → -1 < 1) |
18 | 13, 14, 17 | mp2an 691 | . . . . . . . 8 ⊢ -1 < 1 |
19 | 12, 18 | gtneii 11357 | . . . . . . 7 ⊢ 1 ≠ -1 |
20 | 19 | neii 2939 | . . . . . 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 1135 | . . . . 5 ⊢ ((𝐴 ∈ ℝ* ∧ 𝐴 < 0 ∧ -1 = -1) → 𝐴 < 0) | |
24 | 23 | 3expia 1119 | . . . 4 ⊢ ((𝐴 ∈ ℝ* ∧ 𝐴 < 0) → (-1 = -1 → 𝐴 < 0)) |
25 | 1, 3, 5, 7, 11, 22, 24 | sgn3da 34161 | . . 3 ⊢ (𝐴 ∈ ℝ* → ((sgn‘𝐴) = -1 → 𝐴 < 0)) |
26 | 25 | imp 406 | . 2 ⊢ ((𝐴 ∈ ℝ* ∧ (sgn‘𝐴) = -1) → 𝐴 < 0) |
27 | sgnn 15074 | . 2 ⊢ ((𝐴 ∈ ℝ* ∧ 𝐴 < 0) → (sgn‘𝐴) = -1) | |
28 | 26, 27 | impbida 800 | 1 ⊢ (𝐴 ∈ ℝ* → ((sgn‘𝐴) = -1 ↔ 𝐴 < 0)) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 205 ∧ wa 395 = wceq 1534 ∈ wcel 2099 class class class wbr 5148 ‘cfv 6548 0cc0 11139 1c1 11140 ℝ*cxr 11278 < clt 11279 -cneg 11476 sgncsgn 15066 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1790 ax-4 1804 ax-5 1906 ax-6 1964 ax-7 2004 ax-8 2101 ax-9 2109 ax-10 2130 ax-11 2147 ax-12 2167 ax-ext 2699 ax-sep 5299 ax-nul 5306 ax-pow 5365 ax-pr 5429 ax-un 7740 ax-cnex 11195 ax-resscn 11196 ax-1cn 11197 ax-icn 11198 ax-addcl 11199 ax-addrcl 11200 ax-mulcl 11201 ax-mulrcl 11202 ax-mulcom 11203 ax-addass 11204 ax-mulass 11205 ax-distr 11206 ax-i2m1 11207 ax-1ne0 11208 ax-1rid 11209 ax-rnegex 11210 ax-rrecex 11211 ax-cnre 11212 ax-pre-lttri 11213 ax-pre-lttrn 11214 ax-pre-ltadd 11215 ax-pre-mulgt0 11216 |
This theorem depends on definitions: df-bi 206 df-an 396 df-or 847 df-3or 1086 df-3an 1087 df-tru 1537 df-fal 1547 df-ex 1775 df-nf 1779 df-sb 2061 df-mo 2530 df-eu 2559 df-clab 2706 df-cleq 2720 df-clel 2806 df-nfc 2881 df-ne 2938 df-nel 3044 df-ral 3059 df-rex 3068 df-reu 3374 df-rab 3430 df-v 3473 df-sbc 3777 df-csb 3893 df-dif 3950 df-un 3952 df-in 3954 df-ss 3964 df-nul 4324 df-if 4530 df-pw 4605 df-sn 4630 df-pr 4632 df-op 4636 df-uni 4909 df-br 5149 df-opab 5211 df-mpt 5232 df-id 5576 df-po 5590 df-so 5591 df-xp 5684 df-rel 5685 df-cnv 5686 df-co 5687 df-dm 5688 df-rn 5689 df-res 5690 df-ima 5691 df-iota 6500 df-fun 6550 df-fn 6551 df-f 6552 df-f1 6553 df-fo 6554 df-f1o 6555 df-fv 6556 df-riota 7376 df-ov 7423 df-oprab 7424 df-mpo 7425 df-er 8725 df-en 8965 df-dom 8966 df-sdom 8967 df-pnf 11281 df-mnf 11282 df-xr 11283 df-ltxr 11284 df-le 11285 df-sub 11477 df-neg 11478 df-sgn 15067 |
This theorem is referenced by: sgnmulsgn 34169 |
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