Description: Every power class contains the empty set. (Contributed by NM, 25-Oct-2007)
Ref | Expression | ||
---|---|---|---|
Assertion | 0elpw | ⊢ ∅ ∈ 𝒫 𝐴 |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | 0ss | ⊢ ∅ ⊆ 𝐴 | |
2 | 0ex | ⊢ ∅ ∈ V | |
3 | 2 | elpw | ⊢ ( ∅ ∈ 𝒫 𝐴 ↔ ∅ ⊆ 𝐴 ) |
4 | 1 3 | mpbir | ⊢ ∅ ∈ 𝒫 𝐴 |