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Description: The membership relation and the membership predicate agree when the "containing" class is a setvar. Definition 1.6 of Schloeder p. 1. (Contributed by NM, 13-Aug-1995) Replace the first setvar variable with a class variable. (Revised by BJ, 13-Sep-2022)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | epel | ⊢ ( 𝐴 E 𝑥 ↔ 𝐴 ∈ 𝑥 ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | vex | ⊢ 𝑥 ∈ V | |
| 2 | 1 | epeli | ⊢ ( 𝐴 E 𝑥 ↔ 𝐴 ∈ 𝑥 ) |