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Metamath Proof Explorer

Theorem equtrr

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

		Ref	Expression
	Assertion	equtrr	$⊢ x = y \to (z = x \to z = y)$

Step	Hyp	Ref	Expression
1		equtr	$⊢ z = x \to (x = y \to z = y)$
2	1	com12	$⊢ x = y \to (z = x \to z = y)$