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Mirrors > Home > MPE Home > Th. List > Mathboxes > map0cor | Structured version Visualization version GIF version |
Description: A function exists iff an empty codomain is accompanied with an empty domain. (Contributed by Zhi Wang, 1-Oct-2024.) |
Ref | Expression |
---|---|
map0cor.1 | ⊢ (𝜑 → 𝐴 ∈ 𝑉) |
map0cor.2 | ⊢ (𝜑 → 𝐵 ∈ 𝑊) |
Ref | Expression |
---|---|
map0cor | ⊢ (𝜑 → ((𝐵 = ∅ → 𝐴 = ∅) ↔ ∃𝑓 𝑓:𝐴⟶𝐵)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | map0cor.2 | . 2 ⊢ (𝜑 → 𝐵 ∈ 𝑊) | |
2 | map0cor.1 | . 2 ⊢ (𝜑 → 𝐴 ∈ 𝑉) | |
3 | biid 261 | . . . . . . 7 ⊢ (𝐴 ≠ ∅ ↔ 𝐴 ≠ ∅) | |
4 | 3 | necon2bbii 2990 | . . . . . 6 ⊢ (𝐴 = ∅ ↔ ¬ 𝐴 ≠ ∅) |
5 | 4 | imbi2i 336 | . . . . 5 ⊢ ((𝐵 = ∅ → 𝐴 = ∅) ↔ (𝐵 = ∅ → ¬ 𝐴 ≠ ∅)) |
6 | imnan 399 | . . . . 5 ⊢ ((𝐵 = ∅ → ¬ 𝐴 ≠ ∅) ↔ ¬ (𝐵 = ∅ ∧ 𝐴 ≠ ∅)) | |
7 | 5, 6 | bitri 275 | . . . 4 ⊢ ((𝐵 = ∅ → 𝐴 = ∅) ↔ ¬ (𝐵 = ∅ ∧ 𝐴 ≠ ∅)) |
8 | map0g 8923 | . . . . 5 ⊢ ((𝐵 ∈ 𝑊 ∧ 𝐴 ∈ 𝑉) → ((𝐵 ↑m 𝐴) = ∅ ↔ (𝐵 = ∅ ∧ 𝐴 ≠ ∅))) | |
9 | 8 | notbid 318 | . . . 4 ⊢ ((𝐵 ∈ 𝑊 ∧ 𝐴 ∈ 𝑉) → (¬ (𝐵 ↑m 𝐴) = ∅ ↔ ¬ (𝐵 = ∅ ∧ 𝐴 ≠ ∅))) |
10 | 7, 9 | bitr4id 290 | . . 3 ⊢ ((𝐵 ∈ 𝑊 ∧ 𝐴 ∈ 𝑉) → ((𝐵 = ∅ → 𝐴 = ∅) ↔ ¬ (𝐵 ↑m 𝐴) = ∅)) |
11 | neq0 4358 | . . . 4 ⊢ (¬ (𝐵 ↑m 𝐴) = ∅ ↔ ∃𝑓 𝑓 ∈ (𝐵 ↑m 𝐴)) | |
12 | 11 | a1i 11 | . . 3 ⊢ ((𝐵 ∈ 𝑊 ∧ 𝐴 ∈ 𝑉) → (¬ (𝐵 ↑m 𝐴) = ∅ ↔ ∃𝑓 𝑓 ∈ (𝐵 ↑m 𝐴))) |
13 | elmapg 8878 | . . . 4 ⊢ ((𝐵 ∈ 𝑊 ∧ 𝐴 ∈ 𝑉) → (𝑓 ∈ (𝐵 ↑m 𝐴) ↔ 𝑓:𝐴⟶𝐵)) | |
14 | 13 | exbidv 1919 | . . 3 ⊢ ((𝐵 ∈ 𝑊 ∧ 𝐴 ∈ 𝑉) → (∃𝑓 𝑓 ∈ (𝐵 ↑m 𝐴) ↔ ∃𝑓 𝑓:𝐴⟶𝐵)) |
15 | 10, 12, 14 | 3bitrd 305 | . 2 ⊢ ((𝐵 ∈ 𝑊 ∧ 𝐴 ∈ 𝑉) → ((𝐵 = ∅ → 𝐴 = ∅) ↔ ∃𝑓 𝑓:𝐴⟶𝐵)) |
16 | 1, 2, 15 | syl2anc 584 | 1 ⊢ (𝜑 → ((𝐵 = ∅ → 𝐴 = ∅) ↔ ∃𝑓 𝑓:𝐴⟶𝐵)) |
Colors of variables: wff setvar class |
Syntax hints: ¬ wn 3 → wi 4 ↔ wb 206 ∧ wa 395 = wceq 1537 ∃wex 1776 ∈ wcel 2106 ≠ wne 2938 ∅c0 4339 ⟶wf 6559 (class class class)co 7431 ↑m cmap 8865 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1792 ax-4 1806 ax-5 1908 ax-6 1965 ax-7 2005 ax-8 2108 ax-9 2116 ax-10 2139 ax-11 2155 ax-12 2175 ax-ext 2706 ax-sep 5302 ax-nul 5312 ax-pow 5371 ax-pr 5438 ax-un 7754 |
This theorem depends on definitions: df-bi 207 df-an 396 df-or 848 df-3an 1088 df-tru 1540 df-fal 1550 df-ex 1777 df-nf 1781 df-sb 2063 df-mo 2538 df-eu 2567 df-clab 2713 df-cleq 2727 df-clel 2814 df-nfc 2890 df-ne 2939 df-ral 3060 df-rex 3069 df-rab 3434 df-v 3480 df-sbc 3792 df-csb 3909 df-dif 3966 df-un 3968 df-in 3970 df-ss 3980 df-nul 4340 df-if 4532 df-pw 4607 df-sn 4632 df-pr 4634 df-op 4638 df-uni 4913 df-iun 4998 df-br 5149 df-opab 5211 df-mpt 5232 df-id 5583 df-xp 5695 df-rel 5696 df-cnv 5697 df-co 5698 df-dm 5699 df-rn 5700 df-res 5701 df-ima 5702 df-iota 6516 df-fun 6565 df-fn 6566 df-f 6567 df-fv 6571 df-ov 7434 df-oprab 7435 df-mpo 7436 df-1st 8013 df-2nd 8014 df-map 8867 |
This theorem is referenced by: (None) |
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