Theorem onsuci

Description: The successor of an ordinal number is an ordinal number. Corollary 7N(c) of Enderton p. 193. (Contributed by NM, 12-Jun-1994)

	Ref	Expression
Hypothesis	onssi.1	|- A e. On
Assertion	onsuci	|- suc A e. On

Proof

Step	Hyp	Ref	Expression
1		onssi.1	|- A e. On
2		suceloni	|- ( A e. On -> suc A e. On )
3	1 2	ax-mp	|- suc A e. On