Description: The empty category (see 0cat ) is thin. (Contributed by Zhi Wang, 17-Sep-2024)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | 0thinc | ⊢ ∅ ∈ ThinCat |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | 0ex | ⊢ ∅ ∈ V | |
| 2 | base0 | ⊢ ∅ = ( Base ‘ ∅ ) | |
| 3 | 0thincg | ⊢ ( ( ∅ ∈ V ∧ ∅ = ( Base ‘ ∅ ) ) → ∅ ∈ ThinCat ) | |
| 4 | 1 2 3 | mp2an | ⊢ ∅ ∈ ThinCat |