Metamath Proof Explorer


Theorem eqtr4i

Description: An equality transitivity inference. (Contributed by NM, 26-May-1993)

Ref Expression
Hypotheses eqtr4i.1
|- A = B
eqtr4i.2
|- C = B
Assertion eqtr4i
|- A = C

Proof

Step Hyp Ref Expression
1 eqtr4i.1
 |-  A = B
2 eqtr4i.2
 |-  C = B
3 2 eqcomi
 |-  B = C
4 1 3 eqtri
 |-  A = C