Description: A class precomposed with its converse includes the identity relation restricted to its range. (Contributed by BJ, 25-Oct-2026)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | idresrnsscocnv2 | ⊢ ( I ↾ ran 𝐴 ) ⊆ ( 𝐴 ∘ ◡ 𝐴 ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | idresdmsscocnv1 | ⊢ ( I ↾ dom ◡ 𝐴 ) ⊆ ( ◡ ◡ 𝐴 ∘ ◡ 𝐴 ) | |
| 2 | df-rn | ⊢ ran 𝐴 = dom ◡ 𝐴 | |
| 3 | 2 | eqcomi | ⊢ dom ◡ 𝐴 = ran 𝐴 |
| 4 | 3 | reseq2i | ⊢ ( I ↾ dom ◡ 𝐴 ) = ( I ↾ ran 𝐴 ) |
| 5 | cocnvcnv1 | ⊢ ( ◡ ◡ 𝐴 ∘ ◡ 𝐴 ) = ( 𝐴 ∘ ◡ 𝐴 ) | |
| 6 | 1 4 5 | 3sstr3i | ⊢ ( I ↾ ran 𝐴 ) ⊆ ( 𝐴 ∘ ◡ 𝐴 ) |