Description: Any set weakly dominates the empty set. (Contributed by Stefan O'Rear, 11-Feb-2015)
Ref | Expression | ||
---|---|---|---|
Assertion | 0wdom | ⊢ ( 𝑋 ∈ 𝑉 → ∅ ≼* 𝑋 ) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | eqid | ⊢ ∅ = ∅ | |
2 | 1 | orci | ⊢ ( ∅ = ∅ ∨ ∃ 𝑧 𝑧 : 𝑋 –onto→ ∅ ) |
3 | brwdom | ⊢ ( 𝑋 ∈ 𝑉 → ( ∅ ≼* 𝑋 ↔ ( ∅ = ∅ ∨ ∃ 𝑧 𝑧 : 𝑋 –onto→ ∅ ) ) ) | |
4 | 2 3 | mpbiri | ⊢ ( 𝑋 ∈ 𝑉 → ∅ ≼* 𝑋 ) |