Theorem eqtr3 2251

Description: A transitive law for class equality. (Contributed by NM, 20-May-2005.)

Assertion

Ref	Expression
eqtr3	|- ( ( A = C /\ B = C ) -> A = B )

Proof of Theorem eqtr3

Step	Hyp	Ref	Expression
1		eqcom 2233	. 2 |- ( B = C <-> C = B )
2		eqtr 2249	. 2 |- ( ( A = C /\ C = B ) -> A = B )
3	1, 2	sylan2b 287	1 |- ( ( A = C /\ B = C ) -> A = B )

Syntax hints:   -> wi 4   /\ wa 104   = wceq 1398

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-5 1496  ax-gen 1498  ax-4 1559  ax-17 1575  ax-ext 2213

This theorem depends on definitions:  df-bi 117  df-cleq 2224

This theorem is referenced by:  eueq  2978  euind  2994  reuind  3012  ssprsseq  3840  preqsn  3863  eusv1  4555  funopg  5367  funinsn  5386  foco  5579  funopdmsn  5842  mpofun  6133  enq0tr  7714  lteupri  7897  elrealeu  8109  rereceu  8169  receuap  8908  xrltso  10092  xrlttri3  10093  iseqf1olemab  10827  fsumparts  12111  odd2np1  12514  grpinveu  13701  exmidsbthrlem  16750