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Description: If a function value has a member, then its argument is a set. Deduction form of elfvex . (An artifact of our function value definition.) (Contributed by David Moews, 1-May-2017)
| Ref | Expression | ||
|---|---|---|---|
| Hypothesis | elfvexd.1 | ⊢ ( 𝜑 → 𝐴 ∈ ( 𝐵 ‘ 𝐶 ) ) | |
| Assertion | elfvexd | ⊢ ( 𝜑 → 𝐶 ∈ V ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | elfvexd.1 | ⊢ ( 𝜑 → 𝐴 ∈ ( 𝐵 ‘ 𝐶 ) ) | |
| 2 | elfvex | ⊢ ( 𝐴 ∈ ( 𝐵 ‘ 𝐶 ) → 𝐶 ∈ V ) | |
| 3 | 1 2 | syl | ⊢ ( 𝜑 → 𝐶 ∈ V ) |