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Metamath Proof Explorer

Theorem ordtr

Description: An ordinal class is transitive. (Contributed by NM, 3-Apr-1994)

		Ref	Expression
	Assertion	ordtr	$⊢ Ord A \to Tr A$

Step	Hyp	Ref	Expression
1		df-ord	$⊢ Ord A \leftrightarrow (Tr A \land E We A)$
2	1	simplbi	$⊢ Ord A \to Tr A$