| Step | Hyp | Ref | Expression | 
						
							| 0 |  | ccomf | ⊢ compf | 
						
							| 1 |  | vc | ⊢ 𝑐 | 
						
							| 2 |  | cvv | ⊢ V | 
						
							| 3 |  | vx | ⊢ 𝑥 | 
						
							| 4 |  | cbs | ⊢ Base | 
						
							| 5 | 1 | cv | ⊢ 𝑐 | 
						
							| 6 | 5 4 | cfv | ⊢ ( Base ‘ 𝑐 ) | 
						
							| 7 | 6 6 | cxp | ⊢ ( ( Base ‘ 𝑐 )  ×  ( Base ‘ 𝑐 ) ) | 
						
							| 8 |  | vy | ⊢ 𝑦 | 
						
							| 9 |  | vg | ⊢ 𝑔 | 
						
							| 10 |  | c2nd | ⊢ 2nd | 
						
							| 11 | 3 | cv | ⊢ 𝑥 | 
						
							| 12 | 11 10 | cfv | ⊢ ( 2nd  ‘ 𝑥 ) | 
						
							| 13 |  | chom | ⊢ Hom | 
						
							| 14 | 5 13 | cfv | ⊢ ( Hom  ‘ 𝑐 ) | 
						
							| 15 | 8 | cv | ⊢ 𝑦 | 
						
							| 16 | 12 15 14 | co | ⊢ ( ( 2nd  ‘ 𝑥 ) ( Hom  ‘ 𝑐 ) 𝑦 ) | 
						
							| 17 |  | vf | ⊢ 𝑓 | 
						
							| 18 | 11 14 | cfv | ⊢ ( ( Hom  ‘ 𝑐 ) ‘ 𝑥 ) | 
						
							| 19 | 9 | cv | ⊢ 𝑔 | 
						
							| 20 |  | cco | ⊢ comp | 
						
							| 21 | 5 20 | cfv | ⊢ ( comp ‘ 𝑐 ) | 
						
							| 22 | 11 15 21 | co | ⊢ ( 𝑥 ( comp ‘ 𝑐 ) 𝑦 ) | 
						
							| 23 | 17 | cv | ⊢ 𝑓 | 
						
							| 24 | 19 23 22 | co | ⊢ ( 𝑔 ( 𝑥 ( comp ‘ 𝑐 ) 𝑦 ) 𝑓 ) | 
						
							| 25 | 9 17 16 18 24 | cmpo | ⊢ ( 𝑔  ∈  ( ( 2nd  ‘ 𝑥 ) ( Hom  ‘ 𝑐 ) 𝑦 ) ,  𝑓  ∈  ( ( Hom  ‘ 𝑐 ) ‘ 𝑥 )  ↦  ( 𝑔 ( 𝑥 ( comp ‘ 𝑐 ) 𝑦 ) 𝑓 ) ) | 
						
							| 26 | 3 8 7 6 25 | cmpo | ⊢ ( 𝑥  ∈  ( ( Base ‘ 𝑐 )  ×  ( Base ‘ 𝑐 ) ) ,  𝑦  ∈  ( Base ‘ 𝑐 )  ↦  ( 𝑔  ∈  ( ( 2nd  ‘ 𝑥 ) ( Hom  ‘ 𝑐 ) 𝑦 ) ,  𝑓  ∈  ( ( Hom  ‘ 𝑐 ) ‘ 𝑥 )  ↦  ( 𝑔 ( 𝑥 ( comp ‘ 𝑐 ) 𝑦 ) 𝑓 ) ) ) | 
						
							| 27 | 1 2 26 | cmpt | ⊢ ( 𝑐  ∈  V  ↦  ( 𝑥  ∈  ( ( Base ‘ 𝑐 )  ×  ( Base ‘ 𝑐 ) ) ,  𝑦  ∈  ( Base ‘ 𝑐 )  ↦  ( 𝑔  ∈  ( ( 2nd  ‘ 𝑥 ) ( Hom  ‘ 𝑐 ) 𝑦 ) ,  𝑓  ∈  ( ( Hom  ‘ 𝑐 ) ‘ 𝑥 )  ↦  ( 𝑔 ( 𝑥 ( comp ‘ 𝑐 ) 𝑦 ) 𝑓 ) ) ) ) | 
						
							| 28 | 0 27 | wceq | ⊢ compf  =  ( 𝑐  ∈  V  ↦  ( 𝑥  ∈  ( ( Base ‘ 𝑐 )  ×  ( Base ‘ 𝑐 ) ) ,  𝑦  ∈  ( Base ‘ 𝑐 )  ↦  ( 𝑔  ∈  ( ( 2nd  ‘ 𝑥 ) ( Hom  ‘ 𝑐 ) 𝑦 ) ,  𝑓  ∈  ( ( Hom  ‘ 𝑐 ) ‘ 𝑥 )  ↦  ( 𝑔 ( 𝑥 ( comp ‘ 𝑐 ) 𝑦 ) 𝑓 ) ) ) ) |