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Mirrors > Home > MPE Home > Th. List > Mathboxes > mofsn | Structured version Visualization version GIF version |
Description: There is at most one function into a singleton, with fewer axioms than eufsn 45683 and eufsn2 45684. See also mofsn2 45686. (Contributed by Zhi Wang, 19-Sep-2024.) |
Ref | Expression |
---|---|
mofsn | ⊢ (𝐵 ∈ 𝑉 → ∃*𝑓 𝑓:𝐴⟶{𝐵}) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | fconst2g 6969 | . . . . 5 ⊢ (𝐵 ∈ 𝑉 → (𝑓:𝐴⟶{𝐵} ↔ 𝑓 = (𝐴 × {𝐵}))) | |
2 | 1 | biimpd 232 | . . . 4 ⊢ (𝐵 ∈ 𝑉 → (𝑓:𝐴⟶{𝐵} → 𝑓 = (𝐴 × {𝐵}))) |
3 | fconst2g 6969 | . . . . 5 ⊢ (𝐵 ∈ 𝑉 → (𝑔:𝐴⟶{𝐵} ↔ 𝑔 = (𝐴 × {𝐵}))) | |
4 | 3 | biimpd 232 | . . . 4 ⊢ (𝐵 ∈ 𝑉 → (𝑔:𝐴⟶{𝐵} → 𝑔 = (𝐴 × {𝐵}))) |
5 | eqtr3 2760 | . . . . 5 ⊢ ((𝑓 = (𝐴 × {𝐵}) ∧ 𝑔 = (𝐴 × {𝐵})) → 𝑓 = 𝑔) | |
6 | 5 | a1i 11 | . . . 4 ⊢ (𝐵 ∈ 𝑉 → ((𝑓 = (𝐴 × {𝐵}) ∧ 𝑔 = (𝐴 × {𝐵})) → 𝑓 = 𝑔)) |
7 | 2, 4, 6 | syl2and 611 | . . 3 ⊢ (𝐵 ∈ 𝑉 → ((𝑓:𝐴⟶{𝐵} ∧ 𝑔:𝐴⟶{𝐵}) → 𝑓 = 𝑔)) |
8 | 7 | alrimivv 1934 | . 2 ⊢ (𝐵 ∈ 𝑉 → ∀𝑓∀𝑔((𝑓:𝐴⟶{𝐵} ∧ 𝑔:𝐴⟶{𝐵}) → 𝑓 = 𝑔)) |
9 | feq1 6479 | . . 3 ⊢ (𝑓 = 𝑔 → (𝑓:𝐴⟶{𝐵} ↔ 𝑔:𝐴⟶{𝐵})) | |
10 | 9 | mo4 2566 | . 2 ⊢ (∃*𝑓 𝑓:𝐴⟶{𝐵} ↔ ∀𝑓∀𝑔((𝑓:𝐴⟶{𝐵} ∧ 𝑔:𝐴⟶{𝐵}) → 𝑓 = 𝑔)) |
11 | 8, 10 | sylibr 237 | 1 ⊢ (𝐵 ∈ 𝑉 → ∃*𝑓 𝑓:𝐴⟶{𝐵}) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ∧ wa 399 ∀wal 1540 = wceq 1542 ∈ wcel 2113 ∃*wmo 2538 {csn 4513 × cxp 5517 ⟶wf 6329 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1802 ax-4 1816 ax-5 1916 ax-6 1974 ax-7 2019 ax-8 2115 ax-9 2123 ax-10 2144 ax-11 2161 ax-12 2178 ax-ext 2710 ax-sep 5164 ax-nul 5171 ax-pr 5293 |
This theorem depends on definitions: df-bi 210 df-an 400 df-or 847 df-3an 1090 df-tru 1545 df-fal 1555 df-ex 1787 df-nf 1791 df-sb 2074 df-mo 2540 df-eu 2570 df-clab 2717 df-cleq 2730 df-clel 2811 df-nfc 2881 df-ne 2935 df-ral 3058 df-rex 3059 df-rab 3062 df-v 3399 df-sbc 3680 df-csb 3789 df-dif 3844 df-un 3846 df-in 3848 df-ss 3858 df-nul 4210 df-if 4412 df-sn 4514 df-pr 4516 df-op 4520 df-uni 4794 df-br 5028 df-opab 5090 df-mpt 5108 df-id 5425 df-xp 5525 df-rel 5526 df-cnv 5527 df-co 5528 df-dm 5529 df-rn 5530 df-res 5531 df-ima 5532 df-iota 6291 df-fun 6335 df-fn 6336 df-f 6337 df-fv 6341 |
This theorem is referenced by: mofsn2 45686 |
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