Theorem 3eqtr3g 2226

Description: A chained equality inference, useful for converting from definitions. (Contributed by NM, 15-Nov-1994.)

Hypotheses

Ref	Expression
3eqtr3g.1	|- ( ph -> A = B )
3eqtr3g.2	|- A = C
3eqtr3g.3	|- B = D

Assertion

Ref	Expression
3eqtr3g	|- ( ph -> C = D )

Proof of Theorem 3eqtr3g

Step	Hyp	Ref	Expression
1		3eqtr3g.2	. . 3 |- A = C
2		3eqtr3g.1	. . 3 |- ( ph -> A = B )
3	1, 2	eqtr3id 2217	. 2 |- ( ph -> C = B )
4		3eqtr3g.3	. 2 |- B = D
5	3, 4	eqtrdi 2219	1 |- ( ph -> C = D )

Syntax hints:   -> wi 4   = wceq 1348

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-5 1440  ax-gen 1442  ax-4 1503  ax-17 1519  ax-ext 2152

This theorem depends on definitions:  df-bi 116  df-cleq 2163

This theorem is referenced by:  csbnest1g  3104  disjdif2  3493  dfopg  3763  xpid11  4834  sqxpeq0  5034  cores2  5123  funcoeqres  5473  dftpos2  6240  ine0  8313  fisumcom2  11401  fisum0diag2  11410  mertenslemi1  11498  fprodcom2fi  11589  fprodmodd  11604  4sqlem10  12339  setsslnid  12467  dvmptccn  13473  nninffeq  14053