Description: The number 9 is positive. (Contributed by NM, 27-May-1999)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | 9pos | |- 0 < 9 |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | 8re | |- 8 e. RR |
|
| 2 | 1re | |- 1 e. RR |
|
| 3 | 8pos | |- 0 < 8 |
|
| 4 | 0lt1 | |- 0 < 1 |
|
| 5 | 1 2 3 4 | addgt0ii | |- 0 < ( 8 + 1 ) |
| 6 | df-9 | |- 9 = ( 8 + 1 ) |
|
| 7 | 5 6 | breqtrri | |- 0 < 9 |