Description: The empty category (see 0cat ) is thin. (Contributed by Zhi Wang, 17-Sep-2024)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | 0thinc | |- (/) e. ThinCat |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | 0ex | |- (/) e. _V |
|
| 2 | base0 | |- (/) = ( Base ` (/) ) |
|
| 3 | 0thincg | |- ( ( (/) e. _V /\ (/) = ( Base ` (/) ) ) -> (/) e. ThinCat ) |
|
| 4 | 1 2 3 | mp2an | |- (/) e. ThinCat |