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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 3072 | . . . 4 ⊢ (∀𝑥 ∈ ℝ ¬ ∀𝑦 ∈ 𝐴 𝑥 ≤ 𝑦 ↔ ¬ ∃𝑥 ∈ ℝ ∀𝑦 ∈ 𝐴 𝑥 ≤ 𝑦) | |
2 | ssel2 3940 | . . . . . . . . 9 ⊢ ((𝐴 ⊆ ℝ* ∧ 𝑦 ∈ 𝐴) → 𝑦 ∈ ℝ*) | |
3 | rexr 11206 | . . . . . . . . 9 ⊢ (𝑥 ∈ ℝ → 𝑥 ∈ ℝ*) | |
4 | simpl 484 | . . . . . . . . . 10 ⊢ ((𝑦 ∈ ℝ* ∧ 𝑥 ∈ ℝ*) → 𝑦 ∈ ℝ*) | |
5 | simpr 486 | . . . . . . . . . 10 ⊢ ((𝑦 ∈ ℝ* ∧ 𝑥 ∈ ℝ*) → 𝑥 ∈ ℝ*) | |
6 | 4, 5 | xrltnled 43684 | . . . . . . . . 9 ⊢ ((𝑦 ∈ ℝ* ∧ 𝑥 ∈ ℝ*) → (𝑦 < 𝑥 ↔ ¬ 𝑥 ≤ 𝑦)) |
7 | 2, 3, 6 | syl2an 597 | . . . . . . . 8 ⊢ (((𝐴 ⊆ ℝ* ∧ 𝑦 ∈ 𝐴) ∧ 𝑥 ∈ ℝ) → (𝑦 < 𝑥 ↔ ¬ 𝑥 ≤ 𝑦)) |
8 | 7 | an32s 651 | . . . . . . 7 ⊢ (((𝐴 ⊆ ℝ* ∧ 𝑥 ∈ ℝ) ∧ 𝑦 ∈ 𝐴) → (𝑦 < 𝑥 ↔ ¬ 𝑥 ≤ 𝑦)) |
9 | 8 | rexbidva 3170 | . . . . . 6 ⊢ ((𝐴 ⊆ ℝ* ∧ 𝑥 ∈ ℝ) → (∃𝑦 ∈ 𝐴 𝑦 < 𝑥 ↔ ∃𝑦 ∈ 𝐴 ¬ 𝑥 ≤ 𝑦)) |
10 | rexnal 3100 | . . . . . 6 ⊢ (∃𝑦 ∈ 𝐴 ¬ 𝑥 ≤ 𝑦 ↔ ¬ ∀𝑦 ∈ 𝐴 𝑥 ≤ 𝑦) | |
11 | 9, 10 | bitr2di 288 | . . . . 5 ⊢ ((𝐴 ⊆ ℝ* ∧ 𝑥 ∈ ℝ) → (¬ ∀𝑦 ∈ 𝐴 𝑥 ≤ 𝑦 ↔ ∃𝑦 ∈ 𝐴 𝑦 < 𝑥)) |
12 | 11 | ralbidva 3169 | . . . 4 ⊢ (𝐴 ⊆ ℝ* → (∀𝑥 ∈ ℝ ¬ ∀𝑦 ∈ 𝐴 𝑥 ≤ 𝑦 ↔ ∀𝑥 ∈ ℝ ∃𝑦 ∈ 𝐴 𝑦 < 𝑥)) |
13 | 1, 12 | bitr3id 285 | . . 3 ⊢ (𝐴 ⊆ ℝ* → (¬ ∃𝑥 ∈ ℝ ∀𝑦 ∈ 𝐴 𝑥 ≤ 𝑦 ↔ ∀𝑥 ∈ ℝ ∃𝑦 ∈ 𝐴 𝑦 < 𝑥)) |
14 | infxrunb2 43689 | . . 3 ⊢ (𝐴 ⊆ ℝ* → (∀𝑥 ∈ ℝ ∃𝑦 ∈ 𝐴 𝑦 < 𝑥 ↔ inf(𝐴, ℝ*, < ) = -∞)) | |
15 | infxrcl 13258 | . . . 4 ⊢ (𝐴 ⊆ ℝ* → inf(𝐴, ℝ*, < ) ∈ ℝ*) | |
16 | ngtmnft 13091 | . . . 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 305 | . 2 ⊢ (𝐴 ⊆ ℝ* → (¬ ∃𝑥 ∈ ℝ ∀𝑦 ∈ 𝐴 𝑥 ≤ 𝑦 ↔ ¬ -∞ < inf(𝐴, ℝ*, < ))) |
19 | 18 | con4bid 317 | 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 205 ∧ wa 397 = wceq 1542 ∈ wcel 2107 ∀wral 3061 ∃wrex 3070 ⊆ wss 3911 class class class wbr 5106 infcinf 9382 ℝcr 11055 -∞cmnf 11192 ℝ*cxr 11193 < clt 11194 ≤ cle 11195 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1798 ax-4 1812 ax-5 1914 ax-6 1972 ax-7 2012 ax-8 2109 ax-9 2117 ax-10 2138 ax-11 2155 ax-12 2172 ax-ext 2704 ax-sep 5257 ax-nul 5264 ax-pow 5321 ax-pr 5385 ax-un 7673 ax-cnex 11112 ax-resscn 11113 ax-1cn 11114 ax-icn 11115 ax-addcl 11116 ax-addrcl 11117 ax-mulcl 11118 ax-mulrcl 11119 ax-mulcom 11120 ax-addass 11121 ax-mulass 11122 ax-distr 11123 ax-i2m1 11124 ax-1ne0 11125 ax-1rid 11126 ax-rnegex 11127 ax-rrecex 11128 ax-cnre 11129 ax-pre-lttri 11130 ax-pre-lttrn 11131 ax-pre-ltadd 11132 ax-pre-mulgt0 11133 ax-pre-sup 11134 |
This theorem depends on definitions: df-bi 206 df-an 398 df-or 847 df-3or 1089 df-3an 1090 df-tru 1545 df-fal 1555 df-ex 1783 df-nf 1787 df-sb 2069 df-mo 2535 df-eu 2564 df-clab 2711 df-cleq 2725 df-clel 2811 df-nfc 2886 df-ne 2941 df-nel 3047 df-ral 3062 df-rex 3071 df-rmo 3352 df-reu 3353 df-rab 3407 df-v 3446 df-sbc 3741 df-csb 3857 df-dif 3914 df-un 3916 df-in 3918 df-ss 3928 df-nul 4284 df-if 4488 df-pw 4563 df-sn 4588 df-pr 4590 df-op 4594 df-uni 4867 df-br 5107 df-opab 5169 df-mpt 5190 df-id 5532 df-po 5546 df-so 5547 df-xp 5640 df-rel 5641 df-cnv 5642 df-co 5643 df-dm 5644 df-rn 5645 df-res 5646 df-ima 5647 df-iota 6449 df-fun 6499 df-fn 6500 df-f 6501 df-f1 6502 df-fo 6503 df-f1o 6504 df-fv 6505 df-riota 7314 df-ov 7361 df-oprab 7362 df-mpo 7363 df-er 8651 df-en 8887 df-dom 8888 df-sdom 8889 df-sup 9383 df-inf 9384 df-pnf 11196 df-mnf 11197 df-xr 11198 df-ltxr 11199 df-le 11200 df-sub 11392 df-neg 11393 |
This theorem is referenced by: infleinf 43693 |
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