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Mirrors > Home > NFE Home > Th. List > pssss | Unicode version |
Description: A proper subclass is a subclass. Theorem 10 of [Suppes] p. 23. (Contributed by NM, 7-Feb-1996.) |
Ref | Expression |
---|---|
pssss |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | df-pss 3261 | . 2 | |
2 | 1 | simplbi 446 | 1 |
Colors of variables: wff setvar class |
Syntax hints: wi 4 wne 2516 wss 3257 wpss 3258 |
This theorem was proved from axioms: ax-1 5 ax-2 6 ax-3 7 ax-mp 8 |
This theorem depends on definitions: df-bi 177 df-an 360 df-pss 3261 |
This theorem is referenced by: pssssd 3366 sspss 3368 pssn2lp 3370 psstr 3373 |
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