Theorem eqtr3 2059

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 2042	. 2 |- ( B = C <-> C = B )
2		eqtr 2057	. 2 |- ( ( A = C /\ C = B ) -> A = B )
3	1, 2	sylan2b 271	1 |- ( ( A = C /\ B = C ) -> A = B )

Syntax hints:   -> wi 4   /\ wa 97   = wceq 1243

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-ia3 101  ax-5 1336  ax-gen 1338  ax-4 1400  ax-17 1419  ax-ext 2022

This theorem depends on definitions:  df-bi 110  df-cleq 2033

This theorem is referenced by:  eueq  2712  euind  2728  reuind  2744  preqsn  3546  eusv1  4184  funopg  4934  foco  5116  mpt2fun  5603  enq0tr  6532  lteupri  6715  elrealeu  6906  rereceu  6963  receuap  7650  xrltso  8717  xrlttri3  8718