Description: If A belongs to a part of C , then A belongs to C . (Contributed by FL, 3-Aug-2009)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | elelpwi | ⊢ ( ( 𝐴 ∈ 𝐵 ∧ 𝐵 ∈ 𝒫 𝐶 ) → 𝐴 ∈ 𝐶 ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | elpwi | ⊢ ( 𝐵 ∈ 𝒫 𝐶 → 𝐵 ⊆ 𝐶 ) | |
| 2 | 1 | sseld | ⊢ ( 𝐵 ∈ 𝒫 𝐶 → ( 𝐴 ∈ 𝐵 → 𝐴 ∈ 𝐶 ) ) |
| 3 | 2 | impcom | ⊢ ( ( 𝐴 ∈ 𝐵 ∧ 𝐵 ∈ 𝒫 𝐶 ) → 𝐴 ∈ 𝐶 ) |