Theorem pssn2lp 3604

Description: Proper subclass has no 2-cycle loops. Compare Theorem 8 of [Suppes] p. 23. (Contributed by NM, 7-Feb-1996.) (Proof shortened by Andrew Salmon, 26-Jun-2011.)

Assertion

Ref	Expression
pssn2lp

Proof of Theorem pssn2lp

Step	Hyp	Ref	Expression
1		dfpss3 3589	. . . 4
2	1	simprbi 464	. . 3
3		pssss 3598	. . 3
4	2, 3	nsyl 121	. 2
5		imnan 422	. 2
6	4, 5	mpbi 208	1

Syntax hints:  -.wn 3  ->wi 4  /\wa 369  C_wss 3475  C.wpss 3476

This theorem is referenced by:  psstr  3607  cvnsym  27209

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1618  ax-4 1631  ax-5 1704  ax-6 1747  ax-7 1790  ax-10 1837  ax-11 1842  ax-12 1854  ax-13 1999  ax-ext 2435

This theorem depends on definitions:  df-bi 185  df-an 371  df-tru 1398  df-ex 1613  df-nf 1617  df-sb 1740  df-clab 2443  df-cleq 2449  df-clel 2452  df-ne 2654  df-in 3482  df-ss 3489  df-pss 3491