Theorem 4lt9

Description: 4 is less than 9. (Contributed by Mario Carneiro, 9-Mar-2015)

	Ref	Expression
Assertion	4lt9	⊢ 4 < 9

Proof

Step	Hyp	Ref	Expression
1		4lt5	⊢ 4 < 5
2		5lt9	⊢ 5 < 9
3		4re	⊢ 4 ∈ ℝ
4		5re	⊢ 5 ∈ ℝ
5		9re	⊢ 9 ∈ ℝ
6	3 4 5	lttri	⊢ ( ( 4 < 5 ∧ 5 < 9 ) → 4 < 9 )
7	1 2 6	mp2an	⊢ 4 < 9