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Description: Equality of a class variable and a class abstraction (inference form). (Contributed by NM, 31-Jul-1994) (Proof shortened by Wolf Lammen, 15-Nov-2019)
| Ref | Expression | ||
|---|---|---|---|
| Hypothesis | eqabcri.1 | ⊢ { 𝑥 ∣ 𝜑 } = 𝐴 | |
| Assertion | eqabcri | ⊢ ( 𝜑 ↔ 𝑥 ∈ 𝐴 ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | eqabcri.1 | ⊢ { 𝑥 ∣ 𝜑 } = 𝐴 | |
| 2 | 1 | eqcomi | ⊢ 𝐴 = { 𝑥 ∣ 𝜑 } |
| 3 | 2 | eqabri | ⊢ ( 𝑥 ∈ 𝐴 ↔ 𝜑 ) |
| 4 | 3 | bicomi | ⊢ ( 𝜑 ↔ 𝑥 ∈ 𝐴 ) |