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Mirrors > Home > ILE Home > Th. List > pssv | GIF version |
Description: Any non-universal class is a proper subclass of the universal class. (Contributed by NM, 17-May-1998.) |
Ref | Expression |
---|---|
pssv | ⊢ (𝐴 ⊊ V ↔ ¬ 𝐴 = V) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | ssv 2965 | . 2 ⊢ 𝐴 ⊆ V | |
2 | dfpss2 3029 | . 2 ⊢ (𝐴 ⊊ V ↔ (𝐴 ⊆ V ∧ ¬ 𝐴 = V)) | |
3 | 1, 2 | mpbiran 847 | 1 ⊢ (𝐴 ⊊ V ↔ ¬ 𝐴 = V) |
Colors of variables: wff set class |
Syntax hints: ¬ wn 3 ↔ wb 98 = wceq 1243 Vcvv 2557 ⊆ wss 2917 ⊊ wpss 2918 |
This theorem was proved from axioms: ax-1 5 ax-2 6 ax-mp 7 ax-ia1 99 ax-ia2 100 ax-ia3 101 ax-5 1336 ax-7 1337 ax-gen 1338 ax-ie1 1382 ax-ie2 1383 ax-8 1395 ax-11 1397 ax-4 1400 ax-17 1419 ax-i9 1423 ax-ial 1427 ax-i5r 1428 ax-ext 2022 |
This theorem depends on definitions: df-bi 110 df-nf 1350 df-sb 1646 df-clab 2027 df-cleq 2033 df-clel 2036 df-ne 2206 df-v 2559 df-in 2924 df-ss 2931 df-pss 2933 |
This theorem is referenced by: (None) |
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