Mathbox for Glauco Siliprandi |
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Mirrors > Home > MPE Home > Th. List > Mathboxes > infxrbnd2 | Structured version Visualization version GIF version |
Description: The infimum of a bounded-below set of extended reals is greater than minus infinity. (Contributed by Glauco Siliprandi, 3-Mar-2021.) |
Ref | Expression |
---|---|
infxrbnd2 | ⊢ (𝐴 ⊆ ℝ* → (∃𝑥 ∈ ℝ ∀𝑦 ∈ 𝐴 𝑥 ≤ 𝑦 ↔ -∞ < inf(𝐴, ℝ*, < ))) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | ralnex 3233 | . . . 4 ⊢ (∀𝑥 ∈ ℝ ¬ ∀𝑦 ∈ 𝐴 𝑥 ≤ 𝑦 ↔ ¬ ∃𝑥 ∈ ℝ ∀𝑦 ∈ 𝐴 𝑥 ≤ 𝑦) | |
2 | ssel2 3959 | . . . . . . . . 9 ⊢ ((𝐴 ⊆ ℝ* ∧ 𝑦 ∈ 𝐴) → 𝑦 ∈ ℝ*) | |
3 | rexr 10675 | . . . . . . . . 9 ⊢ (𝑥 ∈ ℝ → 𝑥 ∈ ℝ*) | |
4 | simpl 483 | . . . . . . . . . 10 ⊢ ((𝑦 ∈ ℝ* ∧ 𝑥 ∈ ℝ*) → 𝑦 ∈ ℝ*) | |
5 | simpr 485 | . . . . . . . . . 10 ⊢ ((𝑦 ∈ ℝ* ∧ 𝑥 ∈ ℝ*) → 𝑥 ∈ ℝ*) | |
6 | 4, 5 | xrltnled 41507 | . . . . . . . . 9 ⊢ ((𝑦 ∈ ℝ* ∧ 𝑥 ∈ ℝ*) → (𝑦 < 𝑥 ↔ ¬ 𝑥 ≤ 𝑦)) |
7 | 2, 3, 6 | syl2an 595 | . . . . . . . 8 ⊢ (((𝐴 ⊆ ℝ* ∧ 𝑦 ∈ 𝐴) ∧ 𝑥 ∈ ℝ) → (𝑦 < 𝑥 ↔ ¬ 𝑥 ≤ 𝑦)) |
8 | 7 | an32s 648 | . . . . . . 7 ⊢ (((𝐴 ⊆ ℝ* ∧ 𝑥 ∈ ℝ) ∧ 𝑦 ∈ 𝐴) → (𝑦 < 𝑥 ↔ ¬ 𝑥 ≤ 𝑦)) |
9 | 8 | rexbidva 3293 | . . . . . 6 ⊢ ((𝐴 ⊆ ℝ* ∧ 𝑥 ∈ ℝ) → (∃𝑦 ∈ 𝐴 𝑦 < 𝑥 ↔ ∃𝑦 ∈ 𝐴 ¬ 𝑥 ≤ 𝑦)) |
10 | rexnal 3235 | . . . . . 6 ⊢ (∃𝑦 ∈ 𝐴 ¬ 𝑥 ≤ 𝑦 ↔ ¬ ∀𝑦 ∈ 𝐴 𝑥 ≤ 𝑦) | |
11 | 9, 10 | syl6rbb 289 | . . . . 5 ⊢ ((𝐴 ⊆ ℝ* ∧ 𝑥 ∈ ℝ) → (¬ ∀𝑦 ∈ 𝐴 𝑥 ≤ 𝑦 ↔ ∃𝑦 ∈ 𝐴 𝑦 < 𝑥)) |
12 | 11 | ralbidva 3193 | . . . 4 ⊢ (𝐴 ⊆ ℝ* → (∀𝑥 ∈ ℝ ¬ ∀𝑦 ∈ 𝐴 𝑥 ≤ 𝑦 ↔ ∀𝑥 ∈ ℝ ∃𝑦 ∈ 𝐴 𝑦 < 𝑥)) |
13 | 1, 12 | syl5bbr 286 | . . 3 ⊢ (𝐴 ⊆ ℝ* → (¬ ∃𝑥 ∈ ℝ ∀𝑦 ∈ 𝐴 𝑥 ≤ 𝑦 ↔ ∀𝑥 ∈ ℝ ∃𝑦 ∈ 𝐴 𝑦 < 𝑥)) |
14 | infxrunb2 41512 | . . 3 ⊢ (𝐴 ⊆ ℝ* → (∀𝑥 ∈ ℝ ∃𝑦 ∈ 𝐴 𝑦 < 𝑥 ↔ inf(𝐴, ℝ*, < ) = -∞)) | |
15 | infxrcl 12714 | . . . 4 ⊢ (𝐴 ⊆ ℝ* → inf(𝐴, ℝ*, < ) ∈ ℝ*) | |
16 | ngtmnft 12547 | . . . 4 ⊢ (inf(𝐴, ℝ*, < ) ∈ ℝ* → (inf(𝐴, ℝ*, < ) = -∞ ↔ ¬ -∞ < inf(𝐴, ℝ*, < ))) | |
17 | 15, 16 | syl 17 | . . 3 ⊢ (𝐴 ⊆ ℝ* → (inf(𝐴, ℝ*, < ) = -∞ ↔ ¬ -∞ < inf(𝐴, ℝ*, < ))) |
18 | 13, 14, 17 | 3bitrd 306 | . 2 ⊢ (𝐴 ⊆ ℝ* → (¬ ∃𝑥 ∈ ℝ ∀𝑦 ∈ 𝐴 𝑥 ≤ 𝑦 ↔ ¬ -∞ < inf(𝐴, ℝ*, < ))) |
19 | 18 | con4bid 318 | 1 ⊢ (𝐴 ⊆ ℝ* → (∃𝑥 ∈ ℝ ∀𝑦 ∈ 𝐴 𝑥 ≤ 𝑦 ↔ -∞ < inf(𝐴, ℝ*, < ))) |
Colors of variables: wff setvar class |
Syntax hints: ¬ wn 3 → wi 4 ↔ wb 207 ∧ wa 396 = wceq 1528 ∈ wcel 2105 ∀wral 3135 ∃wrex 3136 ⊆ wss 3933 class class class wbr 5057 infcinf 8893 ℝcr 10524 -∞cmnf 10661 ℝ*cxr 10662 < clt 10663 ≤ cle 10664 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1787 ax-4 1801 ax-5 1902 ax-6 1961 ax-7 2006 ax-8 2107 ax-9 2115 ax-10 2136 ax-11 2151 ax-12 2167 ax-ext 2790 ax-sep 5194 ax-nul 5201 ax-pow 5257 ax-pr 5320 ax-un 7450 ax-cnex 10581 ax-resscn 10582 ax-1cn 10583 ax-icn 10584 ax-addcl 10585 ax-addrcl 10586 ax-mulcl 10587 ax-mulrcl 10588 ax-mulcom 10589 ax-addass 10590 ax-mulass 10591 ax-distr 10592 ax-i2m1 10593 ax-1ne0 10594 ax-1rid 10595 ax-rnegex 10596 ax-rrecex 10597 ax-cnre 10598 ax-pre-lttri 10599 ax-pre-lttrn 10600 ax-pre-ltadd 10601 ax-pre-mulgt0 10602 ax-pre-sup 10603 |
This theorem depends on definitions: df-bi 208 df-an 397 df-or 842 df-3or 1080 df-3an 1081 df-tru 1531 df-ex 1772 df-nf 1776 df-sb 2061 df-mo 2615 df-eu 2647 df-clab 2797 df-cleq 2811 df-clel 2890 df-nfc 2960 df-ne 3014 df-nel 3121 df-ral 3140 df-rex 3141 df-reu 3142 df-rmo 3143 df-rab 3144 df-v 3494 df-sbc 3770 df-csb 3881 df-dif 3936 df-un 3938 df-in 3940 df-ss 3949 df-nul 4289 df-if 4464 df-pw 4537 df-sn 4558 df-pr 4560 df-op 4564 df-uni 4831 df-br 5058 df-opab 5120 df-mpt 5138 df-id 5453 df-po 5467 df-so 5468 df-xp 5554 df-rel 5555 df-cnv 5556 df-co 5557 df-dm 5558 df-rn 5559 df-res 5560 df-ima 5561 df-iota 6307 df-fun 6350 df-fn 6351 df-f 6352 df-f1 6353 df-fo 6354 df-f1o 6355 df-fv 6356 df-riota 7103 df-ov 7148 df-oprab 7149 df-mpo 7150 df-er 8278 df-en 8498 df-dom 8499 df-sdom 8500 df-sup 8894 df-inf 8895 df-pnf 10665 df-mnf 10666 df-xr 10667 df-ltxr 10668 df-le 10669 df-sub 10860 df-neg 10861 |
This theorem is referenced by: infleinf 41516 |
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