![]() |
Mathbox for Thierry Arnoux |
< Previous
Next >
Nearby theorems |
|
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 2728 | . . . . 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 2728 | . . . . 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 2728 | . . . . 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 12327 | . . . . . . 7 ⊢ -1 ≠ 0 | |
9 | 8 | nesymi 2990 | . . . . . 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 12326 | . . . . . . . 8 ⊢ -1 ∈ ℝ | |
13 | neg1lt0 12328 | . . . . . . . . 9 ⊢ -1 < 0 | |
14 | 0lt1 11735 | . . . . . . . . 9 ⊢ 0 < 1 | |
15 | 0re 11215 | . . . . . . . . . 10 ⊢ 0 ∈ ℝ | |
16 | 1re 11213 | . . . . . . . . . 10 ⊢ 1 ∈ ℝ | |
17 | 12, 15, 16 | lttri 11339 | . . . . . . . . 9 ⊢ ((-1 < 0 ∧ 0 < 1) → -1 < 1) |
18 | 13, 14, 17 | mp2an 689 | . . . . . . . 8 ⊢ -1 < 1 |
19 | 12, 18 | gtneii 11325 | . . . . . . 7 ⊢ 1 ≠ -1 |
20 | 19 | neii 2934 | . . . . . 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 1134 | . . . . 5 ⊢ ((𝐴 ∈ ℝ* ∧ 𝐴 < 0 ∧ -1 = -1) → 𝐴 < 0) | |
24 | 23 | 3expia 1118 | . . . 4 ⊢ ((𝐴 ∈ ℝ* ∧ 𝐴 < 0) → (-1 = -1 → 𝐴 < 0)) |
25 | 1, 3, 5, 7, 11, 22, 24 | sgn3da 34060 | . . 3 ⊢ (𝐴 ∈ ℝ* → ((sgn‘𝐴) = -1 → 𝐴 < 0)) |
26 | 25 | imp 406 | . 2 ⊢ ((𝐴 ∈ ℝ* ∧ (sgn‘𝐴) = -1) → 𝐴 < 0) |
27 | sgnn 15043 | . 2 ⊢ ((𝐴 ∈ ℝ* ∧ 𝐴 < 0) → (sgn‘𝐴) = -1) | |
28 | 26, 27 | impbida 798 | 1 ⊢ (𝐴 ∈ ℝ* → ((sgn‘𝐴) = -1 ↔ 𝐴 < 0)) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 205 ∧ wa 395 = wceq 1533 ∈ wcel 2098 class class class wbr 5139 ‘cfv 6534 0cc0 11107 1c1 11108 ℝ*cxr 11246 < clt 11247 -cneg 11444 sgncsgn 15035 |
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-pow 5354 ax-pr 5418 ax-un 7719 ax-cnex 11163 ax-resscn 11164 ax-1cn 11165 ax-icn 11166 ax-addcl 11167 ax-addrcl 11168 ax-mulcl 11169 ax-mulrcl 11170 ax-mulcom 11171 ax-addass 11172 ax-mulass 11173 ax-distr 11174 ax-i2m1 11175 ax-1ne0 11176 ax-1rid 11177 ax-rnegex 11178 ax-rrecex 11179 ax-cnre 11180 ax-pre-lttri 11181 ax-pre-lttrn 11182 ax-pre-ltadd 11183 ax-pre-mulgt0 11184 |
This theorem depends on definitions: df-bi 206 df-an 396 df-or 845 df-3or 1085 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-nel 3039 df-ral 3054 df-rex 3063 df-reu 3369 df-rab 3425 df-v 3468 df-sbc 3771 df-csb 3887 df-dif 3944 df-un 3946 df-in 3948 df-ss 3958 df-nul 4316 df-if 4522 df-pw 4597 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-po 5579 df-so 5580 df-xp 5673 df-rel 5674 df-cnv 5675 df-co 5676 df-dm 5677 df-rn 5678 df-res 5679 df-ima 5680 df-iota 6486 df-fun 6536 df-fn 6537 df-f 6538 df-f1 6539 df-fo 6540 df-f1o 6541 df-fv 6542 df-riota 7358 df-ov 7405 df-oprab 7406 df-mpo 7407 df-er 8700 df-en 8937 df-dom 8938 df-sdom 8939 df-pnf 11249 df-mnf 11250 df-xr 11251 df-ltxr 11252 df-le 11253 df-sub 11445 df-neg 11446 df-sgn 15036 |
This theorem is referenced by: sgnmulsgn 34068 |
Copyright terms: Public domain | W3C validator |