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Mirrors > Home > MPE Home > Th. List > 0pss | Structured version Visualization version GIF version |
Description: The null set is a proper subset of any nonempty set. (Contributed by NM, 27-Feb-1996.) |
Ref | Expression |
---|---|
0pss | ⊢ (∅ ⊊ 𝐴 ↔ 𝐴 ≠ ∅) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | 0ss 4392 | . . 3 ⊢ ∅ ⊆ 𝐴 | |
2 | df-pss 3964 | . . 3 ⊢ (∅ ⊊ 𝐴 ↔ (∅ ⊆ 𝐴 ∧ ∅ ≠ 𝐴)) | |
3 | 1, 2 | mpbiran 708 | . 2 ⊢ (∅ ⊊ 𝐴 ↔ ∅ ≠ 𝐴) |
4 | necom 2990 | . 2 ⊢ (∅ ≠ 𝐴 ↔ 𝐴 ≠ ∅) | |
5 | 3, 4 | bitri 275 | 1 ⊢ (∅ ⊊ 𝐴 ↔ 𝐴 ≠ ∅) |
Colors of variables: wff setvar class |
Syntax hints: ↔ wb 205 ≠ wne 2936 ⊆ wss 3945 ⊊ wpss 3946 ∅c0 4318 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1790 ax-4 1804 ax-5 1906 ax-6 1964 ax-7 2004 ax-8 2101 ax-9 2109 ax-ext 2699 |
This theorem depends on definitions: df-bi 206 df-an 396 df-tru 1537 df-fal 1547 df-ex 1775 df-sb 2061 df-clab 2706 df-cleq 2720 df-clel 2806 df-ne 2937 df-v 3472 df-dif 3948 df-in 3952 df-ss 3962 df-pss 3964 df-nul 4319 |
This theorem is referenced by: php 9228 phpOLD 9240 zornn0g 10522 prn0 11006 genpn0 11020 nqpr 11031 ltexprlem5 11057 reclem2pr 11065 suplem1pr 11069 alexsubALTlem4 23947 bj-2upln0 36496 bj-2upln1upl 36497 0pssin 43195 |
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