Description: An element of a power class is a subclass. Deduction form of elpwi . (Contributed by David Moews, 1-May-2017)
Ref | Expression | ||
---|---|---|---|
Hypothesis | elpwid.1 | ⊢ ( 𝜑 → 𝐴 ∈ 𝒫 𝐵 ) | |
Assertion | elpwid | ⊢ ( 𝜑 → 𝐴 ⊆ 𝐵 ) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | elpwid.1 | ⊢ ( 𝜑 → 𝐴 ∈ 𝒫 𝐵 ) | |
2 | elpwi | ⊢ ( 𝐴 ∈ 𝒫 𝐵 → 𝐴 ⊆ 𝐵 ) | |
3 | 1 2 | syl | ⊢ ( 𝜑 → 𝐴 ⊆ 𝐵 ) |