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Mirrors > Home > ILE Home > Th. List > nmnfgt | GIF version |
Description: An extended real is greater than minus infinite iff they are not equal. (Contributed by Jim Kingdon, 17-Apr-2023.) |
Ref | Expression |
---|---|
nmnfgt | ⊢ (𝐴 ∈ ℝ* → (-∞ < 𝐴 ↔ 𝐴 ≠ -∞)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | ngtmnft 9744 | . . . 4 ⊢ (𝐴 ∈ ℝ* → (𝐴 = -∞ ↔ ¬ -∞ < 𝐴)) | |
2 | 1 | biimpd 143 | . . 3 ⊢ (𝐴 ∈ ℝ* → (𝐴 = -∞ → ¬ -∞ < 𝐴)) |
3 | 2 | necon2ad 2391 | . 2 ⊢ (𝐴 ∈ ℝ* → (-∞ < 𝐴 → 𝐴 ≠ -∞)) |
4 | mnflt 9710 | . . . . 5 ⊢ (𝐴 ∈ ℝ → -∞ < 𝐴) | |
5 | 4 | adantl 275 | . . . 4 ⊢ (((𝐴 ∈ ℝ* ∧ 𝐴 ≠ -∞) ∧ 𝐴 ∈ ℝ) → -∞ < 𝐴) |
6 | mnfltpnf 9712 | . . . . . 6 ⊢ -∞ < +∞ | |
7 | breq2 3980 | . . . . . 6 ⊢ (𝐴 = +∞ → (-∞ < 𝐴 ↔ -∞ < +∞)) | |
8 | 6, 7 | mpbiri 167 | . . . . 5 ⊢ (𝐴 = +∞ → -∞ < 𝐴) |
9 | 8 | adantl 275 | . . . 4 ⊢ (((𝐴 ∈ ℝ* ∧ 𝐴 ≠ -∞) ∧ 𝐴 = +∞) → -∞ < 𝐴) |
10 | simpr 109 | . . . . 5 ⊢ (((𝐴 ∈ ℝ* ∧ 𝐴 ≠ -∞) ∧ 𝐴 = -∞) → 𝐴 = -∞) | |
11 | simplr 520 | . . . . 5 ⊢ (((𝐴 ∈ ℝ* ∧ 𝐴 ≠ -∞) ∧ 𝐴 = -∞) → 𝐴 ≠ -∞) | |
12 | 10, 11 | pm2.21ddne 2417 | . . . 4 ⊢ (((𝐴 ∈ ℝ* ∧ 𝐴 ≠ -∞) ∧ 𝐴 = -∞) → -∞ < 𝐴) |
13 | elxr 9703 | . . . . . 6 ⊢ (𝐴 ∈ ℝ* ↔ (𝐴 ∈ ℝ ∨ 𝐴 = +∞ ∨ 𝐴 = -∞)) | |
14 | 13 | biimpi 119 | . . . . 5 ⊢ (𝐴 ∈ ℝ* → (𝐴 ∈ ℝ ∨ 𝐴 = +∞ ∨ 𝐴 = -∞)) |
15 | 14 | adantr 274 | . . . 4 ⊢ ((𝐴 ∈ ℝ* ∧ 𝐴 ≠ -∞) → (𝐴 ∈ ℝ ∨ 𝐴 = +∞ ∨ 𝐴 = -∞)) |
16 | 5, 9, 12, 15 | mpjao3dan 1296 | . . 3 ⊢ ((𝐴 ∈ ℝ* ∧ 𝐴 ≠ -∞) → -∞ < 𝐴) |
17 | 16 | ex 114 | . 2 ⊢ (𝐴 ∈ ℝ* → (𝐴 ≠ -∞ → -∞ < 𝐴)) |
18 | 3, 17 | impbid 128 | 1 ⊢ (𝐴 ∈ ℝ* → (-∞ < 𝐴 ↔ 𝐴 ≠ -∞)) |
Colors of variables: wff set class |
Syntax hints: ¬ wn 3 → wi 4 ∧ wa 103 ↔ wb 104 ∨ w3o 966 = wceq 1342 ∈ wcel 2135 ≠ wne 2334 class class class wbr 3976 ℝcr 7743 +∞cpnf 7921 -∞cmnf 7922 ℝ*cxr 7923 < clt 7924 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-ia1 105 ax-ia2 106 ax-ia3 107 ax-in1 604 ax-in2 605 ax-io 699 ax-5 1434 ax-7 1435 ax-gen 1436 ax-ie1 1480 ax-ie2 1481 ax-8 1491 ax-10 1492 ax-11 1493 ax-i12 1494 ax-bndl 1496 ax-4 1497 ax-17 1513 ax-i9 1517 ax-ial 1521 ax-i5r 1522 ax-13 2137 ax-14 2138 ax-ext 2146 ax-sep 4094 ax-pow 4147 ax-pr 4181 ax-un 4405 ax-setind 4508 ax-cnex 7835 ax-resscn 7836 ax-pre-ltirr 7856 |
This theorem depends on definitions: df-bi 116 df-3or 968 df-3an 969 df-tru 1345 df-fal 1348 df-nf 1448 df-sb 1750 df-eu 2016 df-mo 2017 df-clab 2151 df-cleq 2157 df-clel 2160 df-nfc 2295 df-ne 2335 df-nel 2430 df-ral 2447 df-rex 2448 df-rab 2451 df-v 2723 df-dif 3113 df-un 3115 df-in 3117 df-ss 3124 df-pw 3555 df-sn 3576 df-pr 3577 df-op 3579 df-uni 3784 df-br 3977 df-opab 4038 df-xp 4604 df-pnf 7926 df-mnf 7927 df-xr 7928 df-ltxr 7929 |
This theorem is referenced by: xlt2add 9807 xrmaxadd 11188 xblpnfps 12939 xblpnf 12940 |
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