Theorem 3eqtr3g 2222

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 2213	. 2 |- ( ph -> C = B )
4		3eqtr3g.3	. 2 |- B = D
5	3, 4	eqtrdi 2215	1 |- ( ph -> C = D )

Syntax hints:   -> wi 4   = wceq 1343

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 1435  ax-gen 1437  ax-4 1498  ax-17 1514  ax-ext 2147

This theorem depends on definitions:  df-bi 116  df-cleq 2158

This theorem is referenced by:  csbnest1g  3100  disjdif2  3487  dfopg  3756  xpid11  4827  sqxpeq0  5027  cores2  5116  funcoeqres  5463  dftpos2  6229  ine0  8292  fisumcom2  11379  fisum0diag2  11388  mertenslemi1  11476  fprodcom2fi  11567  fprodmodd  11582  4sqlem10  12317  setsslnid  12445  dvmptccn  13319  nninffeq  13900