| Step | Hyp | Ref | Expression | 
						
							| 1 |  | ciclcl | ⊢ ( ( 𝐶  ∈  Cat  ∧  𝑅 (  ≃𝑐  ‘ 𝐶 ) 𝑆 )  →  𝑅  ∈  ( Base ‘ 𝐶 ) ) | 
						
							| 2 |  | cicrcl | ⊢ ( ( 𝐶  ∈  Cat  ∧  𝑅 (  ≃𝑐  ‘ 𝐶 ) 𝑆 )  →  𝑆  ∈  ( Base ‘ 𝐶 ) ) | 
						
							| 3 | 1 2 | jca | ⊢ ( ( 𝐶  ∈  Cat  ∧  𝑅 (  ≃𝑐  ‘ 𝐶 ) 𝑆 )  →  ( 𝑅  ∈  ( Base ‘ 𝐶 )  ∧  𝑆  ∈  ( Base ‘ 𝐶 ) ) ) | 
						
							| 4 | 3 | ex | ⊢ ( 𝐶  ∈  Cat  →  ( 𝑅 (  ≃𝑐  ‘ 𝐶 ) 𝑆  →  ( 𝑅  ∈  ( Base ‘ 𝐶 )  ∧  𝑆  ∈  ( Base ‘ 𝐶 ) ) ) ) | 
						
							| 5 |  | cicrcl | ⊢ ( ( 𝐶  ∈  Cat  ∧  𝑆 (  ≃𝑐  ‘ 𝐶 ) 𝑇 )  →  𝑇  ∈  ( Base ‘ 𝐶 ) ) | 
						
							| 6 | 5 | ex | ⊢ ( 𝐶  ∈  Cat  →  ( 𝑆 (  ≃𝑐  ‘ 𝐶 ) 𝑇  →  𝑇  ∈  ( Base ‘ 𝐶 ) ) ) | 
						
							| 7 | 4 6 | anim12d | ⊢ ( 𝐶  ∈  Cat  →  ( ( 𝑅 (  ≃𝑐  ‘ 𝐶 ) 𝑆  ∧  𝑆 (  ≃𝑐  ‘ 𝐶 ) 𝑇 )  →  ( ( 𝑅  ∈  ( Base ‘ 𝐶 )  ∧  𝑆  ∈  ( Base ‘ 𝐶 ) )  ∧  𝑇  ∈  ( Base ‘ 𝐶 ) ) ) ) | 
						
							| 8 | 7 | 3impib | ⊢ ( ( 𝐶  ∈  Cat  ∧  𝑅 (  ≃𝑐  ‘ 𝐶 ) 𝑆  ∧  𝑆 (  ≃𝑐  ‘ 𝐶 ) 𝑇 )  →  ( ( 𝑅  ∈  ( Base ‘ 𝐶 )  ∧  𝑆  ∈  ( Base ‘ 𝐶 ) )  ∧  𝑇  ∈  ( Base ‘ 𝐶 ) ) ) | 
						
							| 9 |  | eqid | ⊢ ( Iso ‘ 𝐶 )  =  ( Iso ‘ 𝐶 ) | 
						
							| 10 |  | eqid | ⊢ ( Base ‘ 𝐶 )  =  ( Base ‘ 𝐶 ) | 
						
							| 11 |  | simpl | ⊢ ( ( 𝐶  ∈  Cat  ∧  ( ( 𝑅  ∈  ( Base ‘ 𝐶 )  ∧  𝑆  ∈  ( Base ‘ 𝐶 ) )  ∧  𝑇  ∈  ( Base ‘ 𝐶 ) ) )  →  𝐶  ∈  Cat ) | 
						
							| 12 |  | simpll | ⊢ ( ( ( 𝑅  ∈  ( Base ‘ 𝐶 )  ∧  𝑆  ∈  ( Base ‘ 𝐶 ) )  ∧  𝑇  ∈  ( Base ‘ 𝐶 ) )  →  𝑅  ∈  ( Base ‘ 𝐶 ) ) | 
						
							| 13 | 12 | adantl | ⊢ ( ( 𝐶  ∈  Cat  ∧  ( ( 𝑅  ∈  ( Base ‘ 𝐶 )  ∧  𝑆  ∈  ( Base ‘ 𝐶 ) )  ∧  𝑇  ∈  ( Base ‘ 𝐶 ) ) )  →  𝑅  ∈  ( Base ‘ 𝐶 ) ) | 
						
							| 14 |  | simplr | ⊢ ( ( ( 𝑅  ∈  ( Base ‘ 𝐶 )  ∧  𝑆  ∈  ( Base ‘ 𝐶 ) )  ∧  𝑇  ∈  ( Base ‘ 𝐶 ) )  →  𝑆  ∈  ( Base ‘ 𝐶 ) ) | 
						
							| 15 | 14 | adantl | ⊢ ( ( 𝐶  ∈  Cat  ∧  ( ( 𝑅  ∈  ( Base ‘ 𝐶 )  ∧  𝑆  ∈  ( Base ‘ 𝐶 ) )  ∧  𝑇  ∈  ( Base ‘ 𝐶 ) ) )  →  𝑆  ∈  ( Base ‘ 𝐶 ) ) | 
						
							| 16 | 9 10 11 13 15 | cic | ⊢ ( ( 𝐶  ∈  Cat  ∧  ( ( 𝑅  ∈  ( Base ‘ 𝐶 )  ∧  𝑆  ∈  ( Base ‘ 𝐶 ) )  ∧  𝑇  ∈  ( Base ‘ 𝐶 ) ) )  →  ( 𝑅 (  ≃𝑐  ‘ 𝐶 ) 𝑆  ↔  ∃ 𝑓 𝑓  ∈  ( 𝑅 ( Iso ‘ 𝐶 ) 𝑆 ) ) ) | 
						
							| 17 |  | simprr | ⊢ ( ( 𝐶  ∈  Cat  ∧  ( ( 𝑅  ∈  ( Base ‘ 𝐶 )  ∧  𝑆  ∈  ( Base ‘ 𝐶 ) )  ∧  𝑇  ∈  ( Base ‘ 𝐶 ) ) )  →  𝑇  ∈  ( Base ‘ 𝐶 ) ) | 
						
							| 18 | 9 10 11 15 17 | cic | ⊢ ( ( 𝐶  ∈  Cat  ∧  ( ( 𝑅  ∈  ( Base ‘ 𝐶 )  ∧  𝑆  ∈  ( Base ‘ 𝐶 ) )  ∧  𝑇  ∈  ( Base ‘ 𝐶 ) ) )  →  ( 𝑆 (  ≃𝑐  ‘ 𝐶 ) 𝑇  ↔  ∃ 𝑔 𝑔  ∈  ( 𝑆 ( Iso ‘ 𝐶 ) 𝑇 ) ) ) | 
						
							| 19 | 16 18 | anbi12d | ⊢ ( ( 𝐶  ∈  Cat  ∧  ( ( 𝑅  ∈  ( Base ‘ 𝐶 )  ∧  𝑆  ∈  ( Base ‘ 𝐶 ) )  ∧  𝑇  ∈  ( Base ‘ 𝐶 ) ) )  →  ( ( 𝑅 (  ≃𝑐  ‘ 𝐶 ) 𝑆  ∧  𝑆 (  ≃𝑐  ‘ 𝐶 ) 𝑇 )  ↔  ( ∃ 𝑓 𝑓  ∈  ( 𝑅 ( Iso ‘ 𝐶 ) 𝑆 )  ∧  ∃ 𝑔 𝑔  ∈  ( 𝑆 ( Iso ‘ 𝐶 ) 𝑇 ) ) ) ) | 
						
							| 20 | 11 | adantl | ⊢ ( ( ( 𝑔  ∈  ( 𝑆 ( Iso ‘ 𝐶 ) 𝑇 )  ∧  𝑓  ∈  ( 𝑅 ( Iso ‘ 𝐶 ) 𝑆 ) )  ∧  ( 𝐶  ∈  Cat  ∧  ( ( 𝑅  ∈  ( Base ‘ 𝐶 )  ∧  𝑆  ∈  ( Base ‘ 𝐶 ) )  ∧  𝑇  ∈  ( Base ‘ 𝐶 ) ) ) )  →  𝐶  ∈  Cat ) | 
						
							| 21 | 13 | adantl | ⊢ ( ( ( 𝑔  ∈  ( 𝑆 ( Iso ‘ 𝐶 ) 𝑇 )  ∧  𝑓  ∈  ( 𝑅 ( Iso ‘ 𝐶 ) 𝑆 ) )  ∧  ( 𝐶  ∈  Cat  ∧  ( ( 𝑅  ∈  ( Base ‘ 𝐶 )  ∧  𝑆  ∈  ( Base ‘ 𝐶 ) )  ∧  𝑇  ∈  ( Base ‘ 𝐶 ) ) ) )  →  𝑅  ∈  ( Base ‘ 𝐶 ) ) | 
						
							| 22 | 17 | adantl | ⊢ ( ( ( 𝑔  ∈  ( 𝑆 ( Iso ‘ 𝐶 ) 𝑇 )  ∧  𝑓  ∈  ( 𝑅 ( Iso ‘ 𝐶 ) 𝑆 ) )  ∧  ( 𝐶  ∈  Cat  ∧  ( ( 𝑅  ∈  ( Base ‘ 𝐶 )  ∧  𝑆  ∈  ( Base ‘ 𝐶 ) )  ∧  𝑇  ∈  ( Base ‘ 𝐶 ) ) ) )  →  𝑇  ∈  ( Base ‘ 𝐶 ) ) | 
						
							| 23 |  | eqid | ⊢ ( comp ‘ 𝐶 )  =  ( comp ‘ 𝐶 ) | 
						
							| 24 | 15 | adantl | ⊢ ( ( ( 𝑔  ∈  ( 𝑆 ( Iso ‘ 𝐶 ) 𝑇 )  ∧  𝑓  ∈  ( 𝑅 ( Iso ‘ 𝐶 ) 𝑆 ) )  ∧  ( 𝐶  ∈  Cat  ∧  ( ( 𝑅  ∈  ( Base ‘ 𝐶 )  ∧  𝑆  ∈  ( Base ‘ 𝐶 ) )  ∧  𝑇  ∈  ( Base ‘ 𝐶 ) ) ) )  →  𝑆  ∈  ( Base ‘ 𝐶 ) ) | 
						
							| 25 |  | simplr | ⊢ ( ( ( 𝑔  ∈  ( 𝑆 ( Iso ‘ 𝐶 ) 𝑇 )  ∧  𝑓  ∈  ( 𝑅 ( Iso ‘ 𝐶 ) 𝑆 ) )  ∧  ( 𝐶  ∈  Cat  ∧  ( ( 𝑅  ∈  ( Base ‘ 𝐶 )  ∧  𝑆  ∈  ( Base ‘ 𝐶 ) )  ∧  𝑇  ∈  ( Base ‘ 𝐶 ) ) ) )  →  𝑓  ∈  ( 𝑅 ( Iso ‘ 𝐶 ) 𝑆 ) ) | 
						
							| 26 |  | simpll | ⊢ ( ( ( 𝑔  ∈  ( 𝑆 ( Iso ‘ 𝐶 ) 𝑇 )  ∧  𝑓  ∈  ( 𝑅 ( Iso ‘ 𝐶 ) 𝑆 ) )  ∧  ( 𝐶  ∈  Cat  ∧  ( ( 𝑅  ∈  ( Base ‘ 𝐶 )  ∧  𝑆  ∈  ( Base ‘ 𝐶 ) )  ∧  𝑇  ∈  ( Base ‘ 𝐶 ) ) ) )  →  𝑔  ∈  ( 𝑆 ( Iso ‘ 𝐶 ) 𝑇 ) ) | 
						
							| 27 | 10 23 9 20 21 24 22 25 26 | isoco | ⊢ ( ( ( 𝑔  ∈  ( 𝑆 ( Iso ‘ 𝐶 ) 𝑇 )  ∧  𝑓  ∈  ( 𝑅 ( Iso ‘ 𝐶 ) 𝑆 ) )  ∧  ( 𝐶  ∈  Cat  ∧  ( ( 𝑅  ∈  ( Base ‘ 𝐶 )  ∧  𝑆  ∈  ( Base ‘ 𝐶 ) )  ∧  𝑇  ∈  ( Base ‘ 𝐶 ) ) ) )  →  ( 𝑔 ( 〈 𝑅 ,  𝑆 〉 ( comp ‘ 𝐶 ) 𝑇 ) 𝑓 )  ∈  ( 𝑅 ( Iso ‘ 𝐶 ) 𝑇 ) ) | 
						
							| 28 | 9 10 20 21 22 27 | brcici | ⊢ ( ( ( 𝑔  ∈  ( 𝑆 ( Iso ‘ 𝐶 ) 𝑇 )  ∧  𝑓  ∈  ( 𝑅 ( Iso ‘ 𝐶 ) 𝑆 ) )  ∧  ( 𝐶  ∈  Cat  ∧  ( ( 𝑅  ∈  ( Base ‘ 𝐶 )  ∧  𝑆  ∈  ( Base ‘ 𝐶 ) )  ∧  𝑇  ∈  ( Base ‘ 𝐶 ) ) ) )  →  𝑅 (  ≃𝑐  ‘ 𝐶 ) 𝑇 ) | 
						
							| 29 | 28 | ex | ⊢ ( ( 𝑔  ∈  ( 𝑆 ( Iso ‘ 𝐶 ) 𝑇 )  ∧  𝑓  ∈  ( 𝑅 ( Iso ‘ 𝐶 ) 𝑆 ) )  →  ( ( 𝐶  ∈  Cat  ∧  ( ( 𝑅  ∈  ( Base ‘ 𝐶 )  ∧  𝑆  ∈  ( Base ‘ 𝐶 ) )  ∧  𝑇  ∈  ( Base ‘ 𝐶 ) ) )  →  𝑅 (  ≃𝑐  ‘ 𝐶 ) 𝑇 ) ) | 
						
							| 30 | 29 | ex | ⊢ ( 𝑔  ∈  ( 𝑆 ( Iso ‘ 𝐶 ) 𝑇 )  →  ( 𝑓  ∈  ( 𝑅 ( Iso ‘ 𝐶 ) 𝑆 )  →  ( ( 𝐶  ∈  Cat  ∧  ( ( 𝑅  ∈  ( Base ‘ 𝐶 )  ∧  𝑆  ∈  ( Base ‘ 𝐶 ) )  ∧  𝑇  ∈  ( Base ‘ 𝐶 ) ) )  →  𝑅 (  ≃𝑐  ‘ 𝐶 ) 𝑇 ) ) ) | 
						
							| 31 | 30 | exlimiv | ⊢ ( ∃ 𝑔 𝑔  ∈  ( 𝑆 ( Iso ‘ 𝐶 ) 𝑇 )  →  ( 𝑓  ∈  ( 𝑅 ( Iso ‘ 𝐶 ) 𝑆 )  →  ( ( 𝐶  ∈  Cat  ∧  ( ( 𝑅  ∈  ( Base ‘ 𝐶 )  ∧  𝑆  ∈  ( Base ‘ 𝐶 ) )  ∧  𝑇  ∈  ( Base ‘ 𝐶 ) ) )  →  𝑅 (  ≃𝑐  ‘ 𝐶 ) 𝑇 ) ) ) | 
						
							| 32 | 31 | com12 | ⊢ ( 𝑓  ∈  ( 𝑅 ( Iso ‘ 𝐶 ) 𝑆 )  →  ( ∃ 𝑔 𝑔  ∈  ( 𝑆 ( Iso ‘ 𝐶 ) 𝑇 )  →  ( ( 𝐶  ∈  Cat  ∧  ( ( 𝑅  ∈  ( Base ‘ 𝐶 )  ∧  𝑆  ∈  ( Base ‘ 𝐶 ) )  ∧  𝑇  ∈  ( Base ‘ 𝐶 ) ) )  →  𝑅 (  ≃𝑐  ‘ 𝐶 ) 𝑇 ) ) ) | 
						
							| 33 | 32 | exlimiv | ⊢ ( ∃ 𝑓 𝑓  ∈  ( 𝑅 ( Iso ‘ 𝐶 ) 𝑆 )  →  ( ∃ 𝑔 𝑔  ∈  ( 𝑆 ( Iso ‘ 𝐶 ) 𝑇 )  →  ( ( 𝐶  ∈  Cat  ∧  ( ( 𝑅  ∈  ( Base ‘ 𝐶 )  ∧  𝑆  ∈  ( Base ‘ 𝐶 ) )  ∧  𝑇  ∈  ( Base ‘ 𝐶 ) ) )  →  𝑅 (  ≃𝑐  ‘ 𝐶 ) 𝑇 ) ) ) | 
						
							| 34 | 33 | imp | ⊢ ( ( ∃ 𝑓 𝑓  ∈  ( 𝑅 ( Iso ‘ 𝐶 ) 𝑆 )  ∧  ∃ 𝑔 𝑔  ∈  ( 𝑆 ( Iso ‘ 𝐶 ) 𝑇 ) )  →  ( ( 𝐶  ∈  Cat  ∧  ( ( 𝑅  ∈  ( Base ‘ 𝐶 )  ∧  𝑆  ∈  ( Base ‘ 𝐶 ) )  ∧  𝑇  ∈  ( Base ‘ 𝐶 ) ) )  →  𝑅 (  ≃𝑐  ‘ 𝐶 ) 𝑇 ) ) | 
						
							| 35 | 34 | com12 | ⊢ ( ( 𝐶  ∈  Cat  ∧  ( ( 𝑅  ∈  ( Base ‘ 𝐶 )  ∧  𝑆  ∈  ( Base ‘ 𝐶 ) )  ∧  𝑇  ∈  ( Base ‘ 𝐶 ) ) )  →  ( ( ∃ 𝑓 𝑓  ∈  ( 𝑅 ( Iso ‘ 𝐶 ) 𝑆 )  ∧  ∃ 𝑔 𝑔  ∈  ( 𝑆 ( Iso ‘ 𝐶 ) 𝑇 ) )  →  𝑅 (  ≃𝑐  ‘ 𝐶 ) 𝑇 ) ) | 
						
							| 36 | 19 35 | sylbid | ⊢ ( ( 𝐶  ∈  Cat  ∧  ( ( 𝑅  ∈  ( Base ‘ 𝐶 )  ∧  𝑆  ∈  ( Base ‘ 𝐶 ) )  ∧  𝑇  ∈  ( Base ‘ 𝐶 ) ) )  →  ( ( 𝑅 (  ≃𝑐  ‘ 𝐶 ) 𝑆  ∧  𝑆 (  ≃𝑐  ‘ 𝐶 ) 𝑇 )  →  𝑅 (  ≃𝑐  ‘ 𝐶 ) 𝑇 ) ) | 
						
							| 37 | 36 | ex | ⊢ ( 𝐶  ∈  Cat  →  ( ( ( 𝑅  ∈  ( Base ‘ 𝐶 )  ∧  𝑆  ∈  ( Base ‘ 𝐶 ) )  ∧  𝑇  ∈  ( Base ‘ 𝐶 ) )  →  ( ( 𝑅 (  ≃𝑐  ‘ 𝐶 ) 𝑆  ∧  𝑆 (  ≃𝑐  ‘ 𝐶 ) 𝑇 )  →  𝑅 (  ≃𝑐  ‘ 𝐶 ) 𝑇 ) ) ) | 
						
							| 38 | 37 | com23 | ⊢ ( 𝐶  ∈  Cat  →  ( ( 𝑅 (  ≃𝑐  ‘ 𝐶 ) 𝑆  ∧  𝑆 (  ≃𝑐  ‘ 𝐶 ) 𝑇 )  →  ( ( ( 𝑅  ∈  ( Base ‘ 𝐶 )  ∧  𝑆  ∈  ( Base ‘ 𝐶 ) )  ∧  𝑇  ∈  ( Base ‘ 𝐶 ) )  →  𝑅 (  ≃𝑐  ‘ 𝐶 ) 𝑇 ) ) ) | 
						
							| 39 | 38 | 3impib | ⊢ ( ( 𝐶  ∈  Cat  ∧  𝑅 (  ≃𝑐  ‘ 𝐶 ) 𝑆  ∧  𝑆 (  ≃𝑐  ‘ 𝐶 ) 𝑇 )  →  ( ( ( 𝑅  ∈  ( Base ‘ 𝐶 )  ∧  𝑆  ∈  ( Base ‘ 𝐶 ) )  ∧  𝑇  ∈  ( Base ‘ 𝐶 ) )  →  𝑅 (  ≃𝑐  ‘ 𝐶 ) 𝑇 ) ) | 
						
							| 40 | 8 39 | mpd | ⊢ ( ( 𝐶  ∈  Cat  ∧  𝑅 (  ≃𝑐  ‘ 𝐶 ) 𝑆  ∧  𝑆 (  ≃𝑐  ‘ 𝐶 ) 𝑇 )  →  𝑅 (  ≃𝑐  ‘ 𝐶 ) 𝑇 ) |