Theorem 1p2e3ALT

Description: Alternate proof of 1p2e3 , shorter but using more axioms. (Contributed by David A. Wheeler, 8-Dec-2018) (New usage is discouraged.) (Proof modification is discouraged.)

	Ref	Expression
Assertion	1p2e3ALT	|- ( 1 + 2 ) = 3

Proof

Step	Hyp	Ref	Expression
1		2cn	|- 2 e. CC
2		ax-1cn	|- 1 e. CC
3		2p1e3	|- ( 2 + 1 ) = 3
4	1 2 3	addcomli	|- ( 1 + 2 ) = 3