Description: 5 is less than 9. (Contributed by Mario Carneiro, 9-Mar-2015)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | 5lt9 | ⊢ 5 < 9 | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | 5lt6 | ⊢ 5 < 6 | |
| 2 | 6lt9 | ⊢ 6 < 9 | |
| 3 | 5re | ⊢ 5 ∈ ℝ | |
| 4 | 6re | ⊢ 6 ∈ ℝ | |
| 5 | 9re | ⊢ 9 ∈ ℝ | |
| 6 | 3 4 5 | lttri | ⊢ ( ( 5 < 6 ∧ 6 < 9 ) → 5 < 9 ) | 
| 7 | 1 2 6 | mp2an | ⊢ 5 < 9 |