Theorem 4lt6

Description: 4 is less than 6. (Contributed by Mario Carneiro, 15-Sep-2013)

	Ref	Expression
Assertion	4lt6	|- 4 < 6

Proof

Step	Hyp	Ref	Expression
1		4lt5	|- 4 < 5
2		5lt6	|- 5 < 6
3		4re	|- 4 e. RR
4		5re	|- 5 e. RR
5		6re	|- 6 e. RR
6	3 4 5	lttri	|- ( ( 4 < 5 /\ 5 < 6 ) -> 4 < 6 )
7	1 2 6	mp2an	|- 4 < 6