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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 264 | . . . . . . 7 ⊢ (𝐴 ≠ ∅ ↔ 𝐴 ≠ ∅) | |
4 | 3 | necon2bbii 2983 | . . . . . 6 ⊢ (𝐴 = ∅ ↔ ¬ 𝐴 ≠ ∅) |
5 | 4 | imbi2i 339 | . . . . 5 ⊢ ((𝐵 = ∅ → 𝐴 = ∅) ↔ (𝐵 = ∅ → ¬ 𝐴 ≠ ∅)) |
6 | imnan 403 | . . . . 5 ⊢ ((𝐵 = ∅ → ¬ 𝐴 ≠ ∅) ↔ ¬ (𝐵 = ∅ ∧ 𝐴 ≠ ∅)) | |
7 | 5, 6 | bitri 278 | . . . 4 ⊢ ((𝐵 = ∅ → 𝐴 = ∅) ↔ ¬ (𝐵 = ∅ ∧ 𝐴 ≠ ∅)) |
8 | map0g 8543 | . . . . 5 ⊢ ((𝐵 ∈ 𝑊 ∧ 𝐴 ∈ 𝑉) → ((𝐵 ↑m 𝐴) = ∅ ↔ (𝐵 = ∅ ∧ 𝐴 ≠ ∅))) | |
9 | 8 | notbid 321 | . . . 4 ⊢ ((𝐵 ∈ 𝑊 ∧ 𝐴 ∈ 𝑉) → (¬ (𝐵 ↑m 𝐴) = ∅ ↔ ¬ (𝐵 = ∅ ∧ 𝐴 ≠ ∅))) |
10 | 7, 9 | bitr4id 293 | . . 3 ⊢ ((𝐵 ∈ 𝑊 ∧ 𝐴 ∈ 𝑉) → ((𝐵 = ∅ → 𝐴 = ∅) ↔ ¬ (𝐵 ↑m 𝐴) = ∅)) |
11 | neq0 4246 | . . . 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 8499 | . . . 4 ⊢ ((𝐵 ∈ 𝑊 ∧ 𝐴 ∈ 𝑉) → (𝑓 ∈ (𝐵 ↑m 𝐴) ↔ 𝑓:𝐴⟶𝐵)) | |
14 | 13 | exbidv 1929 | . . 3 ⊢ ((𝐵 ∈ 𝑊 ∧ 𝐴 ∈ 𝑉) → (∃𝑓 𝑓 ∈ (𝐵 ↑m 𝐴) ↔ ∃𝑓 𝑓:𝐴⟶𝐵)) |
15 | 10, 12, 14 | 3bitrd 308 | . 2 ⊢ ((𝐵 ∈ 𝑊 ∧ 𝐴 ∈ 𝑉) → ((𝐵 = ∅ → 𝐴 = ∅) ↔ ∃𝑓 𝑓:𝐴⟶𝐵)) |
16 | 1, 2, 15 | syl2anc 587 | 1 ⊢ (𝜑 → ((𝐵 = ∅ → 𝐴 = ∅) ↔ ∃𝑓 𝑓:𝐴⟶𝐵)) |
Colors of variables: wff setvar class |
Syntax hints: ¬ wn 3 → wi 4 ↔ wb 209 ∧ wa 399 = wceq 1543 ∃wex 1787 ∈ wcel 2112 ≠ wne 2932 ∅c0 4223 ⟶wf 6354 (class class class)co 7191 ↑m cmap 8486 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1803 ax-4 1817 ax-5 1918 ax-6 1976 ax-7 2018 ax-8 2114 ax-9 2122 ax-10 2143 ax-11 2160 ax-12 2177 ax-ext 2708 ax-sep 5177 ax-nul 5184 ax-pow 5243 ax-pr 5307 ax-un 7501 |
This theorem depends on definitions: df-bi 210 df-an 400 df-or 848 df-3an 1091 df-tru 1546 df-fal 1556 df-ex 1788 df-nf 1792 df-sb 2073 df-mo 2539 df-eu 2568 df-clab 2715 df-cleq 2728 df-clel 2809 df-nfc 2879 df-ne 2933 df-ral 3056 df-rex 3057 df-rab 3060 df-v 3400 df-sbc 3684 df-csb 3799 df-dif 3856 df-un 3858 df-in 3860 df-ss 3870 df-nul 4224 df-if 4426 df-pw 4501 df-sn 4528 df-pr 4530 df-op 4534 df-uni 4806 df-iun 4892 df-br 5040 df-opab 5102 df-mpt 5121 df-id 5440 df-xp 5542 df-rel 5543 df-cnv 5544 df-co 5545 df-dm 5546 df-rn 5547 df-res 5548 df-ima 5549 df-iota 6316 df-fun 6360 df-fn 6361 df-f 6362 df-fv 6366 df-ov 7194 df-oprab 7195 df-mpo 7196 df-1st 7739 df-2nd 7740 df-map 8488 |
This theorem is referenced by: (None) |
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