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Theorem pssne 3365
Description: Two classes in a proper subclass relationship are not equal. (Contributed by NM, 16-Feb-2015.)
Assertion
Ref Expression
pssne (ABAB)

Proof of Theorem pssne
StepHypRef Expression
1 df-pss 3261 . 2 (AB ↔ (A B AB))
21simprbi 450 1 (ABAB)
Colors of variables: wff setvar class
Syntax hints:  wi 4  wne 2516   wss 3257  wpss 3258
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8
This theorem depends on definitions:  df-bi 177  df-an 360  df-pss 3261
This theorem is referenced by:  pssned  3367
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