| Step | Hyp | Ref | Expression | 
|---|
| 1 |  | relres 6022 | . . . 4
⊢ Rel ( I
↾ 𝐴) | 
| 2 |  | relin2 5822 | . . . 4
⊢ (Rel ( I
↾ 𝐴) → Rel
(𝑅 ∩ ( I ↾ 𝐴))) | 
| 3 | 1, 2 | mp1i 13 | . . 3
⊢ (𝑅 Po 𝐴 → Rel (𝑅 ∩ ( I ↾ 𝐴))) | 
| 4 |  | df-br 5143 | . . . . 5
⊢ (𝑥(𝑅 ∩ ( I ↾ 𝐴))𝑦 ↔ 〈𝑥, 𝑦〉 ∈ (𝑅 ∩ ( I ↾ 𝐴))) | 
| 5 |  | brin 5194 | . . . . 5
⊢ (𝑥(𝑅 ∩ ( I ↾ 𝐴))𝑦 ↔ (𝑥𝑅𝑦 ∧ 𝑥( I ↾ 𝐴)𝑦)) | 
| 6 | 4, 5 | bitr3i 277 | . . . 4
⊢
(〈𝑥, 𝑦〉 ∈ (𝑅 ∩ ( I ↾ 𝐴)) ↔ (𝑥𝑅𝑦 ∧ 𝑥( I ↾ 𝐴)𝑦)) | 
| 7 |  | vex 3483 | . . . . . . . . 9
⊢ 𝑦 ∈ V | 
| 8 | 7 | brresi 6005 | . . . . . . . 8
⊢ (𝑥( I ↾ 𝐴)𝑦 ↔ (𝑥 ∈ 𝐴 ∧ 𝑥 I 𝑦)) | 
| 9 |  | poirr 5603 | . . . . . . . . . 10
⊢ ((𝑅 Po 𝐴 ∧ 𝑥 ∈ 𝐴) → ¬ 𝑥𝑅𝑥) | 
| 10 | 7 | ideq 5862 | . . . . . . . . . . . 12
⊢ (𝑥 I 𝑦 ↔ 𝑥 = 𝑦) | 
| 11 |  | breq2 5146 | . . . . . . . . . . . 12
⊢ (𝑥 = 𝑦 → (𝑥𝑅𝑥 ↔ 𝑥𝑅𝑦)) | 
| 12 | 10, 11 | sylbi 217 | . . . . . . . . . . 11
⊢ (𝑥 I 𝑦 → (𝑥𝑅𝑥 ↔ 𝑥𝑅𝑦)) | 
| 13 | 12 | notbid 318 | . . . . . . . . . 10
⊢ (𝑥 I 𝑦 → (¬ 𝑥𝑅𝑥 ↔ ¬ 𝑥𝑅𝑦)) | 
| 14 | 9, 13 | syl5ibcom 245 | . . . . . . . . 9
⊢ ((𝑅 Po 𝐴 ∧ 𝑥 ∈ 𝐴) → (𝑥 I 𝑦 → ¬ 𝑥𝑅𝑦)) | 
| 15 | 14 | expimpd 453 | . . . . . . . 8
⊢ (𝑅 Po 𝐴 → ((𝑥 ∈ 𝐴 ∧ 𝑥 I 𝑦) → ¬ 𝑥𝑅𝑦)) | 
| 16 | 8, 15 | biimtrid 242 | . . . . . . 7
⊢ (𝑅 Po 𝐴 → (𝑥( I ↾ 𝐴)𝑦 → ¬ 𝑥𝑅𝑦)) | 
| 17 | 16 | con2d 134 | . . . . . 6
⊢ (𝑅 Po 𝐴 → (𝑥𝑅𝑦 → ¬ 𝑥( I ↾ 𝐴)𝑦)) | 
| 18 |  | imnan 399 | . . . . . 6
⊢ ((𝑥𝑅𝑦 → ¬ 𝑥( I ↾ 𝐴)𝑦) ↔ ¬ (𝑥𝑅𝑦 ∧ 𝑥( I ↾ 𝐴)𝑦)) | 
| 19 | 17, 18 | sylib 218 | . . . . 5
⊢ (𝑅 Po 𝐴 → ¬ (𝑥𝑅𝑦 ∧ 𝑥( I ↾ 𝐴)𝑦)) | 
| 20 | 19 | pm2.21d 121 | . . . 4
⊢ (𝑅 Po 𝐴 → ((𝑥𝑅𝑦 ∧ 𝑥( I ↾ 𝐴)𝑦) → 〈𝑥, 𝑦〉 ∈ ∅)) | 
| 21 | 6, 20 | biimtrid 242 | . . 3
⊢ (𝑅 Po 𝐴 → (〈𝑥, 𝑦〉 ∈ (𝑅 ∩ ( I ↾ 𝐴)) → 〈𝑥, 𝑦〉 ∈ ∅)) | 
| 22 | 3, 21 | relssdv 5797 | . 2
⊢ (𝑅 Po 𝐴 → (𝑅 ∩ ( I ↾ 𝐴)) ⊆ ∅) | 
| 23 |  | ss0 4401 | . 2
⊢ ((𝑅 ∩ ( I ↾ 𝐴)) ⊆ ∅ → (𝑅 ∩ ( I ↾ 𝐴)) = ∅) | 
| 24 | 22, 23 | syl 17 | 1
⊢ (𝑅 Po 𝐴 → (𝑅 ∩ ( I ↾ 𝐴)) = ∅) |