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| Mirrors > Home > MPE Home > Th. List > Mathboxes > elfvne0 | Structured version Visualization version GIF version | ||
| Description: If a function value has a member, then the function is not an empty set (An artifact of our function value definition.) (Contributed by Zhi Wang, 16-Sep-2024.) |
| Ref | Expression |
|---|---|
| elfvne0 | ⊢ (𝐴 ∈ (𝐹‘𝐵) → 𝐹 ≠ ∅) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | ne0i 4294 | . 2 ⊢ (𝐴 ∈ (𝐹‘𝐵) → (𝐹‘𝐵) ≠ ∅) | |
| 2 | fveq1 6880 | . . . 4 ⊢ (𝐹 = ∅ → (𝐹‘𝐵) = (∅‘𝐵)) | |
| 3 | 0fv 6922 | . . . 4 ⊢ (∅‘𝐵) = ∅ | |
| 4 | 2, 3 | eqtrdi 2814 | . . 3 ⊢ (𝐹 = ∅ → (𝐹‘𝐵) = ∅) |
| 5 | 4 | necon3i 2990 | . 2 ⊢ ((𝐹‘𝐵) ≠ ∅ → 𝐹 ≠ ∅) |
| 6 | 1, 5 | syl 18 | 1 ⊢ (𝐴 ∈ (𝐹‘𝐵) → 𝐹 ≠ ∅) |
| Colors of variables: wff setvar class |
| Syntax hints: → wi 4 = wceq 1570 ∈ wcel 2143 ≠ wne 2958 ∅c0 4286 ‘cfv 6536 |
| This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1825 ax-4 1839 ax-5 1940 ax-6 1997 ax-7 2038 ax-8 2145 ax-9 2153 ax-ext 2735 ax-nul 5269 ax-pr 5404 |
| This theorem depends on definitions: df-bi 210 df-an 401 df-or 861 df-3an 1105 df-tru 1573 df-fal 1583 df-ex 1810 df-sb 2097 df-mo 2567 df-eu 2597 df-clab 2742 df-cleq 2755 df-clel 2838 df-ne 2959 df-rab 3417 df-v 3457 df-dif 3908 df-un 3910 df-ss 3922 df-nul 4287 df-if 4488 df-sn 4590 df-pr 4592 df-op 4596 df-uni 4873 df-br 5110 df-dm 5671 df-iota 6492 df-fv 6544 |
| This theorem is referenced by: neircl 49683 sectrcl 49800 invrcl 49802 isorcl 49811 catcrcl 50173 |
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