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| Mirrors > Home > MPE Home > Th. List > Mathboxes > welb | Structured version Visualization version GIF version | ||
| Description: A nonempty subset of a well-ordered set has a lower bound. (Contributed by Jeff Madsen, 2-Sep-2009.) |
| Ref | Expression |
|---|---|
| welb | ⊢ ((𝑅 We 𝐴 ∧ (𝐵 ∈ 𝐶 ∧ 𝐵 ⊆ 𝐴 ∧ 𝐵 ≠ ∅)) → (◡𝑅 Or 𝐵 ∧ ∃𝑥 ∈ 𝐵 (∀𝑦 ∈ 𝐵 ¬ 𝑥◡𝑅𝑦 ∧ ∀𝑦 ∈ 𝐵 (𝑦◡𝑅𝑥 → ∃𝑧 ∈ 𝐵 𝑦◡𝑅𝑧)))) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | wess 5622 | . . . . . 6 ⊢ (𝐵 ⊆ 𝐴 → (𝑅 We 𝐴 → 𝑅 We 𝐵)) | |
| 2 | 1 | impcom 410 | . . . . 5 ⊢ ((𝑅 We 𝐴 ∧ 𝐵 ⊆ 𝐴) → 𝑅 We 𝐵) |
| 3 | weso 5627 | . . . . 5 ⊢ (𝑅 We 𝐵 → 𝑅 Or 𝐵) | |
| 4 | 2, 3 | syl 17 | . . . 4 ⊢ ((𝑅 We 𝐴 ∧ 𝐵 ⊆ 𝐴) → 𝑅 Or 𝐵) |
| 5 | cnvso 6260 | . . . 4 ⊢ (𝑅 Or 𝐵 ↔ ◡𝑅 Or 𝐵) | |
| 6 | 4, 5 | sylib 220 | . . 3 ⊢ ((𝑅 We 𝐴 ∧ 𝐵 ⊆ 𝐴) → ◡𝑅 Or 𝐵) |
| 7 | 6 | 3ad2antr2 1199 | . 2 ⊢ ((𝑅 We 𝐴 ∧ (𝐵 ∈ 𝐶 ∧ 𝐵 ⊆ 𝐴 ∧ 𝐵 ≠ ∅)) → ◡𝑅 Or 𝐵) |
| 8 | wefr 5626 | . . . . 5 ⊢ (𝑅 We 𝐵 → 𝑅 Fr 𝐵) | |
| 9 | 2, 8 | syl 17 | . . . 4 ⊢ ((𝑅 We 𝐴 ∧ 𝐵 ⊆ 𝐴) → 𝑅 Fr 𝐵) |
| 10 | 9 | 3ad2antr2 1199 | . . 3 ⊢ ((𝑅 We 𝐴 ∧ (𝐵 ∈ 𝐶 ∧ 𝐵 ⊆ 𝐴 ∧ 𝐵 ≠ ∅)) → 𝑅 Fr 𝐵) |
| 11 | ssidd 3950 | . . . . 5 ⊢ (𝐵 ⊆ 𝐴 → 𝐵 ⊆ 𝐵) | |
| 12 | 11 | 3anim2i 1162 | . . . 4 ⊢ ((𝐵 ∈ 𝐶 ∧ 𝐵 ⊆ 𝐴 ∧ 𝐵 ≠ ∅) → (𝐵 ∈ 𝐶 ∧ 𝐵 ⊆ 𝐵 ∧ 𝐵 ≠ ∅)) |
| 13 | 12 | adantl 484 | . . 3 ⊢ ((𝑅 We 𝐴 ∧ (𝐵 ∈ 𝐶 ∧ 𝐵 ⊆ 𝐴 ∧ 𝐵 ≠ ∅)) → (𝐵 ∈ 𝐶 ∧ 𝐵 ⊆ 𝐵 ∧ 𝐵 ≠ ∅)) |
| 14 | frinfm 38172 | . . 3 ⊢ ((𝑅 Fr 𝐵 ∧ (𝐵 ∈ 𝐶 ∧ 𝐵 ⊆ 𝐵 ∧ 𝐵 ≠ ∅)) → ∃𝑥 ∈ 𝐵 (∀𝑦 ∈ 𝐵 ¬ 𝑥◡𝑅𝑦 ∧ ∀𝑦 ∈ 𝐵 (𝑦◡𝑅𝑥 → ∃𝑧 ∈ 𝐵 𝑦◡𝑅𝑧))) | |
| 15 | 10, 13, 14 | syl2anc 592 | . 2 ⊢ ((𝑅 We 𝐴 ∧ (𝐵 ∈ 𝐶 ∧ 𝐵 ⊆ 𝐴 ∧ 𝐵 ≠ ∅)) → ∃𝑥 ∈ 𝐵 (∀𝑦 ∈ 𝐵 ¬ 𝑥◡𝑅𝑦 ∧ ∀𝑦 ∈ 𝐵 (𝑦◡𝑅𝑥 → ∃𝑧 ∈ 𝐵 𝑦◡𝑅𝑧))) |
| 16 | 7, 15 | jca 518 | 1 ⊢ ((𝑅 We 𝐴 ∧ (𝐵 ∈ 𝐶 ∧ 𝐵 ⊆ 𝐴 ∧ 𝐵 ≠ ∅)) → (◡𝑅 Or 𝐵 ∧ ∃𝑥 ∈ 𝐵 (∀𝑦 ∈ 𝐵 ¬ 𝑥◡𝑅𝑦 ∧ ∀𝑦 ∈ 𝐵 (𝑦◡𝑅𝑥 → ∃𝑧 ∈ 𝐵 𝑦◡𝑅𝑧)))) |
| Colors of variables: wff setvar class |
| Syntax hints: ¬ wn 3 → wi 4 ∧ wa 398 ∧ w3a 1095 ∈ wcel 2132 ≠ wne 2947 ∀wral 3066 ∃wrex 3076 ⊆ wss 3895 ∅c0 4276 class class class wbr 5090 Or wor 5543 Fr wfr 5586 We wwe 5588 ◡ccnv 5635 |
| This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1805 ax-4 1819 ax-5 1920 ax-6 1977 ax-7 2018 ax-8 2134 ax-9 2142 ax-10 2165 ax-11 2181 ax-12 2202 ax-ext 2724 ax-sep 5236 ax-pr 5380 |
| This theorem depends on definitions: df-bi 209 df-an 399 df-or 857 df-3or 1096 df-3an 1097 df-tru 1553 df-fal 1563 df-ex 1790 df-nf 1794 df-sb 2081 df-clab 2731 df-cleq 2744 df-clel 2827 df-ne 2948 df-ral 3067 df-rex 3077 df-rab 3405 df-v 3446 df-dif 3898 df-un 3900 df-in 3902 df-ss 3912 df-nul 4277 df-if 4471 df-pw 4547 df-sn 4573 df-pr 4575 df-op 4579 df-br 5091 df-opab 5153 df-po 5544 df-so 5545 df-fr 5589 df-we 5591 df-cnv 5644 |
| This theorem is referenced by: (None) |
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