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Mirrors > Home > ILE Home > Th. List > ss0 | GIF version |
Description: Any subset of the empty set is empty. Theorem 5 of [Suppes] p. 23. (Contributed by NM, 13-Aug-1994.) |
Ref | Expression |
---|---|
ss0 | ⊢ (𝐴 ⊆ ∅ → 𝐴 = ∅) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | ss0b 3402 | . 2 ⊢ (𝐴 ⊆ ∅ ↔ 𝐴 = ∅) | |
2 | 1 | biimpi 119 | 1 ⊢ (𝐴 ⊆ ∅ → 𝐴 = ∅) |
Colors of variables: wff set class |
Syntax hints: → wi 4 = wceq 1331 ⊆ wss 3071 ∅c0 3363 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-ia1 105 ax-ia2 106 ax-ia3 107 ax-in1 603 ax-in2 604 ax-io 698 ax-5 1423 ax-7 1424 ax-gen 1425 ax-ie1 1469 ax-ie2 1470 ax-8 1482 ax-10 1483 ax-11 1484 ax-i12 1485 ax-bndl 1486 ax-4 1487 ax-17 1506 ax-i9 1510 ax-ial 1514 ax-i5r 1515 ax-ext 2121 |
This theorem depends on definitions: df-bi 116 df-tru 1334 df-nf 1437 df-sb 1736 df-clab 2126 df-cleq 2132 df-clel 2135 df-nfc 2270 df-v 2688 df-dif 3073 df-in 3077 df-ss 3084 df-nul 3364 |
This theorem is referenced by: sseq0 3404 abf 3406 eq0rdv 3407 ssdisj 3419 0dif 3434 poirr2 4931 iotanul 5103 f00 5314 map0b 6581 phplem2 6747 php5dom 6757 sbthlem7 6851 fi0 6863 casefun 6970 caseinj 6974 djufun 6989 djuinj 6991 exmidomni 7014 ixxdisj 9686 icodisj 9775 ioodisj 9776 uzdisj 9873 nn0disj 9915 fsum2dlemstep 11203 ntrcls0 12300 nninfalllemn 13202 |
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