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Description: Setvar variable membership in a power class. (Contributed by David A. Wheeler, 8-Dec-2018)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | velpw | ⊢ ( 𝑥 ∈ 𝒫 𝐴 ↔ 𝑥 ⊆ 𝐴 ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | vex | ⊢ 𝑥 ∈ V | |
| 2 | 1 | elpw | ⊢ ( 𝑥 ∈ 𝒫 𝐴 ↔ 𝑥 ⊆ 𝐴 ) |