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Theorem equtr 1682
Description: A transitive law for equality. (Contributed by NM, 23-Aug-1993.)
Assertion
Ref Expression
equtr (x = y → (y = zx = z))

Proof of Theorem equtr
StepHypRef Expression
1 ax-8 1675 . 2 (y = x → (y = zx = z))
21equcoms 1681 1 (x = y → (y = zx = z))
Colors of variables: wff setvar class
Syntax hints:  wi 4
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1546  ax-5 1557  ax-17 1616  ax-9 1654  ax-8 1675
This theorem depends on definitions:  df-bi 177  df-ex 1542
This theorem is referenced by:  equtrr  1683  equequ1  1684  equveli  1988  equvin  2001
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