Theorem psstr 3373

Description: Transitive law for proper subclass. Theorem 9 of [Suppes] p. 23. (Contributed by NM, 7-Feb-1996.)

Assertion

Ref	Expression
psstr	|- ((A C. B /\ B C. C) -> A C. C)

Proof of Theorem psstr

Step	Hyp	Ref	Expression
1		pssss 3364	. . 3 |- (A C. B -> A C_ B)
2		pssss 3364	. . 3 |- (B C. C -> B C_ C)
3	1, 2	sylan9ss 3285	. 2 |- ((A C. B /\ B C. C) -> A C_ C)
4		pssn2lp 3370	. . . 4 |- -. (C C. B /\ B C. C)
5		psseq1 3356	. . . . 5 |- (A = C -> (A C. B <-> C C. B))
6	5	anbi1d 685	. . . 4 |- (A = C -> ((A C. B /\ B C. C) <-> (C C. B /\ B C. C)))
7	4, 6	mtbiri 294	. . 3 |- (A = C -> -. (A C. B /\ B C. C))
8	7	con2i 112	. 2 |- ((A C. B /\ B C. C) -> -. A = C)
9		dfpss2 3354	. 2 |- (A C. C <-> (A C_ C /\ -. A = C))
10	3, 8, 9	sylanbrc 645	1 |- ((A C. B /\ B C. C) -> A C. C)

Syntax hints:  -. wn 3   -> wi 4   /\ wa 358   = wceq 1642   C_ wss 3257   C. wpss 3258

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 8  ax-gen 1546  ax-5 1557  ax-17 1616  ax-9 1654  ax-8 1675  ax-6 1729  ax-7 1734  ax-11 1746  ax-12 1925  ax-ext 2334

This theorem depends on definitions:  df-bi 177  df-or 359  df-an 360  df-nan 1288  df-tru 1319  df-ex 1542  df-nf 1545  df-sb 1649  df-clab 2340  df-cleq 2346  df-clel 2349  df-nfc 2478  df-ne 2518  df-v 2861  df-nin 3211  df-compl 3212  df-in 3213  df-ss 3259  df-pss 3261

This theorem is referenced by:  sspsstr  3374  psssstr  3375  psstrd  3376