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Mirrors > Home > ILE Home > Th. List > infm | GIF version |
Description: An infinite set is inhabited. (Contributed by Jim Kingdon, 18-Feb-2022.) |
Ref | Expression |
---|---|
infm | ⊢ (ω ≼ 𝐴 → ∃𝑥 𝑥 ∈ 𝐴) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | brdomi 6746 | . 2 ⊢ (ω ≼ 𝐴 → ∃𝑓 𝑓:ω–1-1→𝐴) | |
2 | f1f 5420 | . . . . 5 ⊢ (𝑓:ω–1-1→𝐴 → 𝑓:ω⟶𝐴) | |
3 | 2 | adantl 277 | . . . 4 ⊢ ((ω ≼ 𝐴 ∧ 𝑓:ω–1-1→𝐴) → 𝑓:ω⟶𝐴) |
4 | peano1 4592 | . . . . 5 ⊢ ∅ ∈ ω | |
5 | 4 | a1i 9 | . . . 4 ⊢ ((ω ≼ 𝐴 ∧ 𝑓:ω–1-1→𝐴) → ∅ ∈ ω) |
6 | 3, 5 | ffvelcdmd 5651 | . . 3 ⊢ ((ω ≼ 𝐴 ∧ 𝑓:ω–1-1→𝐴) → (𝑓‘∅) ∈ 𝐴) |
7 | elex2 2753 | . . 3 ⊢ ((𝑓‘∅) ∈ 𝐴 → ∃𝑥 𝑥 ∈ 𝐴) | |
8 | 6, 7 | syl 14 | . 2 ⊢ ((ω ≼ 𝐴 ∧ 𝑓:ω–1-1→𝐴) → ∃𝑥 𝑥 ∈ 𝐴) |
9 | 1, 8 | exlimddv 1898 | 1 ⊢ (ω ≼ 𝐴 → ∃𝑥 𝑥 ∈ 𝐴) |
Colors of variables: wff set class |
Syntax hints: → wi 4 ∧ wa 104 ∃wex 1492 ∈ wcel 2148 ∅c0 3422 class class class wbr 4002 ωcom 4588 ⟶wf 5211 –1-1→wf1 5212 ‘cfv 5215 ≼ cdom 6736 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-ia1 106 ax-ia2 107 ax-ia3 108 ax-in1 614 ax-in2 615 ax-io 709 ax-5 1447 ax-7 1448 ax-gen 1449 ax-ie1 1493 ax-ie2 1494 ax-8 1504 ax-10 1505 ax-11 1506 ax-i12 1507 ax-bndl 1509 ax-4 1510 ax-17 1526 ax-i9 1530 ax-ial 1534 ax-i5r 1535 ax-13 2150 ax-14 2151 ax-ext 2159 ax-sep 4120 ax-nul 4128 ax-pow 4173 ax-pr 4208 ax-un 4432 |
This theorem depends on definitions: df-bi 117 df-3an 980 df-tru 1356 df-nf 1461 df-sb 1763 df-eu 2029 df-mo 2030 df-clab 2164 df-cleq 2170 df-clel 2173 df-nfc 2308 df-ral 2460 df-rex 2461 df-v 2739 df-sbc 2963 df-dif 3131 df-un 3133 df-in 3135 df-ss 3142 df-nul 3423 df-pw 3577 df-sn 3598 df-pr 3599 df-op 3601 df-uni 3810 df-int 3845 df-br 4003 df-opab 4064 df-id 4292 df-iom 4589 df-xp 4631 df-rel 4632 df-cnv 4633 df-co 4634 df-dm 4635 df-rn 4636 df-iota 5177 df-fun 5217 df-fn 5218 df-f 5219 df-f1 5220 df-fv 5223 df-dom 6739 |
This theorem is referenced by: infn0 6902 inffiexmid 6903 inffinp1 12422 unbendc 12447 |
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