Theorem onunisuci

Description: An ordinal number is equal to the union of its successor. (Contributed by NM, 12-Jun-1994)

	Ref	Expression
Hypothesis	on.1	|- A e. On
Assertion	onunisuci	|- U. suc A = A

Proof

Step	Hyp	Ref	Expression
1		on.1	|- A e. On
2		onunisuc	|- ( A e. On -> U. suc A = A )
3	1 2	ax-mp	|- U. suc A = A