| Step | Hyp | Ref | Expression | 
						
							| 1 |  | sectco.b | ⊢ 𝐵  =  ( Base ‘ 𝐶 ) | 
						
							| 2 |  | sectco.o | ⊢  ·   =  ( comp ‘ 𝐶 ) | 
						
							| 3 |  | sectco.s | ⊢ 𝑆  =  ( Sect ‘ 𝐶 ) | 
						
							| 4 |  | sectco.c | ⊢ ( 𝜑  →  𝐶  ∈  Cat ) | 
						
							| 5 |  | sectco.x | ⊢ ( 𝜑  →  𝑋  ∈  𝐵 ) | 
						
							| 6 |  | sectco.y | ⊢ ( 𝜑  →  𝑌  ∈  𝐵 ) | 
						
							| 7 |  | sectco.z | ⊢ ( 𝜑  →  𝑍  ∈  𝐵 ) | 
						
							| 8 |  | sectco.1 | ⊢ ( 𝜑  →  𝐹 ( 𝑋 𝑆 𝑌 ) 𝐺 ) | 
						
							| 9 |  | sectco.2 | ⊢ ( 𝜑  →  𝐻 ( 𝑌 𝑆 𝑍 ) 𝐾 ) | 
						
							| 10 |  | eqid | ⊢ ( Hom  ‘ 𝐶 )  =  ( Hom  ‘ 𝐶 ) | 
						
							| 11 |  | eqid | ⊢ ( Id ‘ 𝐶 )  =  ( Id ‘ 𝐶 ) | 
						
							| 12 | 1 10 2 11 3 4 5 6 | issect | ⊢ ( 𝜑  →  ( 𝐹 ( 𝑋 𝑆 𝑌 ) 𝐺  ↔  ( 𝐹  ∈  ( 𝑋 ( Hom  ‘ 𝐶 ) 𝑌 )  ∧  𝐺  ∈  ( 𝑌 ( Hom  ‘ 𝐶 ) 𝑋 )  ∧  ( 𝐺 ( 〈 𝑋 ,  𝑌 〉  ·  𝑋 ) 𝐹 )  =  ( ( Id ‘ 𝐶 ) ‘ 𝑋 ) ) ) ) | 
						
							| 13 | 8 12 | mpbid | ⊢ ( 𝜑  →  ( 𝐹  ∈  ( 𝑋 ( Hom  ‘ 𝐶 ) 𝑌 )  ∧  𝐺  ∈  ( 𝑌 ( Hom  ‘ 𝐶 ) 𝑋 )  ∧  ( 𝐺 ( 〈 𝑋 ,  𝑌 〉  ·  𝑋 ) 𝐹 )  =  ( ( Id ‘ 𝐶 ) ‘ 𝑋 ) ) ) | 
						
							| 14 | 13 | simp1d | ⊢ ( 𝜑  →  𝐹  ∈  ( 𝑋 ( Hom  ‘ 𝐶 ) 𝑌 ) ) | 
						
							| 15 | 1 10 2 11 3 4 6 7 | issect | ⊢ ( 𝜑  →  ( 𝐻 ( 𝑌 𝑆 𝑍 ) 𝐾  ↔  ( 𝐻  ∈  ( 𝑌 ( Hom  ‘ 𝐶 ) 𝑍 )  ∧  𝐾  ∈  ( 𝑍 ( Hom  ‘ 𝐶 ) 𝑌 )  ∧  ( 𝐾 ( 〈 𝑌 ,  𝑍 〉  ·  𝑌 ) 𝐻 )  =  ( ( Id ‘ 𝐶 ) ‘ 𝑌 ) ) ) ) | 
						
							| 16 | 9 15 | mpbid | ⊢ ( 𝜑  →  ( 𝐻  ∈  ( 𝑌 ( Hom  ‘ 𝐶 ) 𝑍 )  ∧  𝐾  ∈  ( 𝑍 ( Hom  ‘ 𝐶 ) 𝑌 )  ∧  ( 𝐾 ( 〈 𝑌 ,  𝑍 〉  ·  𝑌 ) 𝐻 )  =  ( ( Id ‘ 𝐶 ) ‘ 𝑌 ) ) ) | 
						
							| 17 | 16 | simp1d | ⊢ ( 𝜑  →  𝐻  ∈  ( 𝑌 ( Hom  ‘ 𝐶 ) 𝑍 ) ) | 
						
							| 18 | 1 10 2 4 5 6 7 14 17 | catcocl | ⊢ ( 𝜑  →  ( 𝐻 ( 〈 𝑋 ,  𝑌 〉  ·  𝑍 ) 𝐹 )  ∈  ( 𝑋 ( Hom  ‘ 𝐶 ) 𝑍 ) ) | 
						
							| 19 | 16 | simp2d | ⊢ ( 𝜑  →  𝐾  ∈  ( 𝑍 ( Hom  ‘ 𝐶 ) 𝑌 ) ) | 
						
							| 20 | 13 | simp2d | ⊢ ( 𝜑  →  𝐺  ∈  ( 𝑌 ( Hom  ‘ 𝐶 ) 𝑋 ) ) | 
						
							| 21 | 1 10 2 4 5 7 6 18 19 5 20 | catass | ⊢ ( 𝜑  →  ( ( 𝐺 ( 〈 𝑍 ,  𝑌 〉  ·  𝑋 ) 𝐾 ) ( 〈 𝑋 ,  𝑍 〉  ·  𝑋 ) ( 𝐻 ( 〈 𝑋 ,  𝑌 〉  ·  𝑍 ) 𝐹 ) )  =  ( 𝐺 ( 〈 𝑋 ,  𝑌 〉  ·  𝑋 ) ( 𝐾 ( 〈 𝑋 ,  𝑍 〉  ·  𝑌 ) ( 𝐻 ( 〈 𝑋 ,  𝑌 〉  ·  𝑍 ) 𝐹 ) ) ) ) | 
						
							| 22 | 16 | simp3d | ⊢ ( 𝜑  →  ( 𝐾 ( 〈 𝑌 ,  𝑍 〉  ·  𝑌 ) 𝐻 )  =  ( ( Id ‘ 𝐶 ) ‘ 𝑌 ) ) | 
						
							| 23 | 22 | oveq1d | ⊢ ( 𝜑  →  ( ( 𝐾 ( 〈 𝑌 ,  𝑍 〉  ·  𝑌 ) 𝐻 ) ( 〈 𝑋 ,  𝑌 〉  ·  𝑌 ) 𝐹 )  =  ( ( ( Id ‘ 𝐶 ) ‘ 𝑌 ) ( 〈 𝑋 ,  𝑌 〉  ·  𝑌 ) 𝐹 ) ) | 
						
							| 24 | 1 10 2 4 5 6 7 14 17 6 19 | catass | ⊢ ( 𝜑  →  ( ( 𝐾 ( 〈 𝑌 ,  𝑍 〉  ·  𝑌 ) 𝐻 ) ( 〈 𝑋 ,  𝑌 〉  ·  𝑌 ) 𝐹 )  =  ( 𝐾 ( 〈 𝑋 ,  𝑍 〉  ·  𝑌 ) ( 𝐻 ( 〈 𝑋 ,  𝑌 〉  ·  𝑍 ) 𝐹 ) ) ) | 
						
							| 25 | 1 10 11 4 5 2 6 14 | catlid | ⊢ ( 𝜑  →  ( ( ( Id ‘ 𝐶 ) ‘ 𝑌 ) ( 〈 𝑋 ,  𝑌 〉  ·  𝑌 ) 𝐹 )  =  𝐹 ) | 
						
							| 26 | 23 24 25 | 3eqtr3d | ⊢ ( 𝜑  →  ( 𝐾 ( 〈 𝑋 ,  𝑍 〉  ·  𝑌 ) ( 𝐻 ( 〈 𝑋 ,  𝑌 〉  ·  𝑍 ) 𝐹 ) )  =  𝐹 ) | 
						
							| 27 | 26 | oveq2d | ⊢ ( 𝜑  →  ( 𝐺 ( 〈 𝑋 ,  𝑌 〉  ·  𝑋 ) ( 𝐾 ( 〈 𝑋 ,  𝑍 〉  ·  𝑌 ) ( 𝐻 ( 〈 𝑋 ,  𝑌 〉  ·  𝑍 ) 𝐹 ) ) )  =  ( 𝐺 ( 〈 𝑋 ,  𝑌 〉  ·  𝑋 ) 𝐹 ) ) | 
						
							| 28 | 13 | simp3d | ⊢ ( 𝜑  →  ( 𝐺 ( 〈 𝑋 ,  𝑌 〉  ·  𝑋 ) 𝐹 )  =  ( ( Id ‘ 𝐶 ) ‘ 𝑋 ) ) | 
						
							| 29 | 21 27 28 | 3eqtrd | ⊢ ( 𝜑  →  ( ( 𝐺 ( 〈 𝑍 ,  𝑌 〉  ·  𝑋 ) 𝐾 ) ( 〈 𝑋 ,  𝑍 〉  ·  𝑋 ) ( 𝐻 ( 〈 𝑋 ,  𝑌 〉  ·  𝑍 ) 𝐹 ) )  =  ( ( Id ‘ 𝐶 ) ‘ 𝑋 ) ) | 
						
							| 30 | 1 10 2 4 7 6 5 19 20 | catcocl | ⊢ ( 𝜑  →  ( 𝐺 ( 〈 𝑍 ,  𝑌 〉  ·  𝑋 ) 𝐾 )  ∈  ( 𝑍 ( Hom  ‘ 𝐶 ) 𝑋 ) ) | 
						
							| 31 | 1 10 2 11 3 4 5 7 18 30 | issect2 | ⊢ ( 𝜑  →  ( ( 𝐻 ( 〈 𝑋 ,  𝑌 〉  ·  𝑍 ) 𝐹 ) ( 𝑋 𝑆 𝑍 ) ( 𝐺 ( 〈 𝑍 ,  𝑌 〉  ·  𝑋 ) 𝐾 )  ↔  ( ( 𝐺 ( 〈 𝑍 ,  𝑌 〉  ·  𝑋 ) 𝐾 ) ( 〈 𝑋 ,  𝑍 〉  ·  𝑋 ) ( 𝐻 ( 〈 𝑋 ,  𝑌 〉  ·  𝑍 ) 𝐹 ) )  =  ( ( Id ‘ 𝐶 ) ‘ 𝑋 ) ) ) | 
						
							| 32 | 29 31 | mpbird | ⊢ ( 𝜑  →  ( 𝐻 ( 〈 𝑋 ,  𝑌 〉  ·  𝑍 ) 𝐹 ) ( 𝑋 𝑆 𝑍 ) ( 𝐺 ( 〈 𝑍 ,  𝑌 〉  ·  𝑋 ) 𝐾 ) ) |