Theorem equtrr 1949

Description: A transitive law for equality. Lemma L17 in [Megill] p. 446 (p. 14 of the preprint). (Contributed by NM, 23-Aug-1993.)

Assertion

Ref	Expression
equtrr	|- ( x = y -> ( z = x -> z = y ) )

Proof of Theorem equtrr

Step	Hyp	Ref	Expression
1		equtr 1948	. 2 |- ( z = x -> ( x = y -> z = y ) )
2	1	com12 32	1 |- ( x = y -> ( z = x -> z = y ) )

Syntax hints:   -> wi 4

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1722  ax-4 1737  ax-5 1839  ax-6 1888  ax-7 1935

This theorem depends on definitions:  df-bi 197  df-an 386  df-ex 1705

This theorem is referenced by:  equeuclr  1950  equequ2  1953  equtr2OLD  1956  equvinv  1959  equvinivOLD  1961  equvinvOLD  1962  equvelv  1963  ax12v2  2049  ax12vOLD  2050  2ax6elem  2449  wl-spae  33306  wl-ax8clv2  33381  ax12eq  34226  sbeqalbi  38601  ax6e2eq  38773  ax6e2eqVD  39143