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Description: Isomorphic objects are isomorphic in the opposite category. (Contributed by Zhi Wang, 26-Oct-2025)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | oppccic.o | ⊢ 𝑂 = ( oppCat ‘ 𝐶 ) | |
| oppccic.i | ⊢ ( 𝜑 → 𝑅 ( ≃𝑐 ‘ 𝐶 ) 𝑆 ) | ||
| Assertion | oppccic | ⊢ ( 𝜑 → 𝑅 ( ≃𝑐 ‘ 𝑂 ) 𝑆 ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | oppccic.o | ⊢ 𝑂 = ( oppCat ‘ 𝐶 ) | |
| 2 | oppccic.i | ⊢ ( 𝜑 → 𝑅 ( ≃𝑐 ‘ 𝐶 ) 𝑆 ) | |
| 3 | cicrcl2 | ⊢ ( 𝑅 ( ≃𝑐 ‘ 𝐶 ) 𝑆 → 𝐶 ∈ Cat ) | |
| 4 | 2 3 | syl | ⊢ ( 𝜑 → 𝐶 ∈ Cat ) |
| 5 | 1 | oppccat | ⊢ ( 𝐶 ∈ Cat → 𝑂 ∈ Cat ) |
| 6 | 4 5 | syl | ⊢ ( 𝜑 → 𝑂 ∈ Cat ) |
| 7 | eqid | ⊢ ( Base ‘ 𝐶 ) = ( Base ‘ 𝐶 ) | |
| 8 | cicrcl | ⊢ ( ( 𝐶 ∈ Cat ∧ 𝑅 ( ≃𝑐 ‘ 𝐶 ) 𝑆 ) → 𝑆 ∈ ( Base ‘ 𝐶 ) ) | |
| 9 | 4 2 8 | syl2anc | ⊢ ( 𝜑 → 𝑆 ∈ ( Base ‘ 𝐶 ) ) |
| 10 | ciclcl | ⊢ ( ( 𝐶 ∈ Cat ∧ 𝑅 ( ≃𝑐 ‘ 𝐶 ) 𝑆 ) → 𝑅 ∈ ( Base ‘ 𝐶 ) ) | |
| 11 | 4 2 10 | syl2anc | ⊢ ( 𝜑 → 𝑅 ∈ ( Base ‘ 𝐶 ) ) |
| 12 | eqid | ⊢ ( Iso ‘ 𝐶 ) = ( Iso ‘ 𝐶 ) | |
| 13 | eqid | ⊢ ( Iso ‘ 𝑂 ) = ( Iso ‘ 𝑂 ) | |
| 14 | 7 1 4 9 11 12 13 | oppciso | ⊢ ( 𝜑 → ( 𝑆 ( Iso ‘ 𝑂 ) 𝑅 ) = ( 𝑅 ( Iso ‘ 𝐶 ) 𝑆 ) ) |
| 15 | 14 | neeq1d | ⊢ ( 𝜑 → ( ( 𝑆 ( Iso ‘ 𝑂 ) 𝑅 ) ≠ ∅ ↔ ( 𝑅 ( Iso ‘ 𝐶 ) 𝑆 ) ≠ ∅ ) ) |
| 16 | 1 7 | oppcbas | ⊢ ( Base ‘ 𝐶 ) = ( Base ‘ 𝑂 ) |
| 17 | 13 16 6 9 11 | brcic | ⊢ ( 𝜑 → ( 𝑆 ( ≃𝑐 ‘ 𝑂 ) 𝑅 ↔ ( 𝑆 ( Iso ‘ 𝑂 ) 𝑅 ) ≠ ∅ ) ) |
| 18 | 12 7 4 11 9 | brcic | ⊢ ( 𝜑 → ( 𝑅 ( ≃𝑐 ‘ 𝐶 ) 𝑆 ↔ ( 𝑅 ( Iso ‘ 𝐶 ) 𝑆 ) ≠ ∅ ) ) |
| 19 | 15 17 18 | 3bitr4rd | ⊢ ( 𝜑 → ( 𝑅 ( ≃𝑐 ‘ 𝐶 ) 𝑆 ↔ 𝑆 ( ≃𝑐 ‘ 𝑂 ) 𝑅 ) ) |
| 20 | 2 19 | mpbid | ⊢ ( 𝜑 → 𝑆 ( ≃𝑐 ‘ 𝑂 ) 𝑅 ) |
| 21 | cicsym | ⊢ ( ( 𝑂 ∈ Cat ∧ 𝑆 ( ≃𝑐 ‘ 𝑂 ) 𝑅 ) → 𝑅 ( ≃𝑐 ‘ 𝑂 ) 𝑆 ) | |
| 22 | 6 20 21 | syl2anc | ⊢ ( 𝜑 → 𝑅 ( ≃𝑐 ‘ 𝑂 ) 𝑆 ) |