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Mirrors > Home > ILE Home > Th. List > n0i | GIF version |
Description: If a set has elements, it is not empty. A set with elements is also inhabited, see elex2 2649. (Contributed by NM, 31-Dec-1993.) |
Ref | Expression |
---|---|
n0i | ⊢ (𝐵 ∈ 𝐴 → ¬ 𝐴 = ∅) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | noel 3306 | . . 3 ⊢ ¬ 𝐵 ∈ ∅ | |
2 | eleq2 2158 | . . 3 ⊢ (𝐴 = ∅ → (𝐵 ∈ 𝐴 ↔ 𝐵 ∈ ∅)) | |
3 | 1, 2 | mtbiri 638 | . 2 ⊢ (𝐴 = ∅ → ¬ 𝐵 ∈ 𝐴) |
4 | 3 | con2i 595 | 1 ⊢ (𝐵 ∈ 𝐴 → ¬ 𝐴 = ∅) |
Colors of variables: wff set class |
Syntax hints: ¬ wn 3 → wi 4 = wceq 1296 ∈ wcel 1445 ∅c0 3302 |
This theorem was proved from axioms: ax-1 5 ax-2 6 ax-mp 7 ax-ia1 105 ax-ia2 106 ax-ia3 107 ax-in1 582 ax-in2 583 ax-io 668 ax-5 1388 ax-7 1389 ax-gen 1390 ax-ie1 1434 ax-ie2 1435 ax-8 1447 ax-10 1448 ax-11 1449 ax-i12 1450 ax-bndl 1451 ax-4 1452 ax-17 1471 ax-i9 1475 ax-ial 1479 ax-i5r 1480 ax-ext 2077 |
This theorem depends on definitions: df-bi 116 df-tru 1299 df-nf 1402 df-sb 1700 df-clab 2082 df-cleq 2088 df-clel 2091 df-nfc 2224 df-v 2635 df-dif 3015 df-nul 3303 |
This theorem is referenced by: ne0i 3308 n0ii 3310 unidif0 4023 iin0r 4025 nnm00 6328 dif1enen 6676 enq0tr 7090 |
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