Theorem 4even

Description: 4 is an even number. (Contributed by AV, 23-Jul-2020)

	Ref	Expression
Assertion	4even	|- 4 e. Even

Proof

Step	Hyp	Ref	Expression
1		3odd	|- 3 e. Odd
2		df-4	|- 4 = ( 3 + 1 )
3		oddp1eveni	|- ( 3 e. Odd -> ( 3 + 1 ) e. Even )
4	2 3	eqeltrid	|- ( 3 e. Odd -> 4 e. Even )
5	1 4	ax-mp	|- 4 e. Even