| Step | Hyp | Ref | Expression | 
						
							| 1 |  | isinag.p | ⊢ 𝑃  =  ( Base ‘ 𝐺 ) | 
						
							| 2 |  | isinag.i | ⊢ 𝐼  =  ( Itv ‘ 𝐺 ) | 
						
							| 3 |  | isinag.k | ⊢ 𝐾  =  ( hlG ‘ 𝐺 ) | 
						
							| 4 |  | isinag.x | ⊢ ( 𝜑  →  𝑋  ∈  𝑃 ) | 
						
							| 5 |  | isinag.a | ⊢ ( 𝜑  →  𝐴  ∈  𝑃 ) | 
						
							| 6 |  | isinag.b | ⊢ ( 𝜑  →  𝐵  ∈  𝑃 ) | 
						
							| 7 |  | isinag.c | ⊢ ( 𝜑  →  𝐶  ∈  𝑃 ) | 
						
							| 8 |  | isinagd.g | ⊢ ( 𝜑  →  𝐺  ∈  𝑉 ) | 
						
							| 9 |  | isinagd.y | ⊢ ( 𝜑  →  𝑌  ∈  𝑃 ) | 
						
							| 10 |  | isinagd.1 | ⊢ ( 𝜑  →  𝐴  ≠  𝐵 ) | 
						
							| 11 |  | isinagd.2 | ⊢ ( 𝜑  →  𝐶  ≠  𝐵 ) | 
						
							| 12 |  | isinagd.3 | ⊢ ( 𝜑  →  𝑋  ≠  𝐵 ) | 
						
							| 13 |  | isinagd.4 | ⊢ ( 𝜑  →  𝑌  ∈  ( 𝐴 𝐼 𝐶 ) ) | 
						
							| 14 |  | isinagd.5 | ⊢ ( 𝜑  →  ( 𝑌  =  𝐵  ∨  𝑌 ( 𝐾 ‘ 𝐵 ) 𝑋 ) ) | 
						
							| 15 | 10 11 12 | 3jca | ⊢ ( 𝜑  →  ( 𝐴  ≠  𝐵  ∧  𝐶  ≠  𝐵  ∧  𝑋  ≠  𝐵 ) ) | 
						
							| 16 |  | simpr | ⊢ ( ( 𝜑  ∧  𝑥  =  𝑌 )  →  𝑥  =  𝑌 ) | 
						
							| 17 |  | eqidd | ⊢ ( ( 𝜑  ∧  𝑥  =  𝑌 )  →  ( 𝐴 𝐼 𝐶 )  =  ( 𝐴 𝐼 𝐶 ) ) | 
						
							| 18 | 16 17 | eleq12d | ⊢ ( ( 𝜑  ∧  𝑥  =  𝑌 )  →  ( 𝑥  ∈  ( 𝐴 𝐼 𝐶 )  ↔  𝑌  ∈  ( 𝐴 𝐼 𝐶 ) ) ) | 
						
							| 19 |  | eqidd | ⊢ ( ( 𝜑  ∧  𝑥  =  𝑌 )  →  𝐵  =  𝐵 ) | 
						
							| 20 | 16 19 | eqeq12d | ⊢ ( ( 𝜑  ∧  𝑥  =  𝑌 )  →  ( 𝑥  =  𝐵  ↔  𝑌  =  𝐵 ) ) | 
						
							| 21 | 16 | breq1d | ⊢ ( ( 𝜑  ∧  𝑥  =  𝑌 )  →  ( 𝑥 ( 𝐾 ‘ 𝐵 ) 𝑋  ↔  𝑌 ( 𝐾 ‘ 𝐵 ) 𝑋 ) ) | 
						
							| 22 | 20 21 | orbi12d | ⊢ ( ( 𝜑  ∧  𝑥  =  𝑌 )  →  ( ( 𝑥  =  𝐵  ∨  𝑥 ( 𝐾 ‘ 𝐵 ) 𝑋 )  ↔  ( 𝑌  =  𝐵  ∨  𝑌 ( 𝐾 ‘ 𝐵 ) 𝑋 ) ) ) | 
						
							| 23 | 18 22 | anbi12d | ⊢ ( ( 𝜑  ∧  𝑥  =  𝑌 )  →  ( ( 𝑥  ∈  ( 𝐴 𝐼 𝐶 )  ∧  ( 𝑥  =  𝐵  ∨  𝑥 ( 𝐾 ‘ 𝐵 ) 𝑋 ) )  ↔  ( 𝑌  ∈  ( 𝐴 𝐼 𝐶 )  ∧  ( 𝑌  =  𝐵  ∨  𝑌 ( 𝐾 ‘ 𝐵 ) 𝑋 ) ) ) ) | 
						
							| 24 | 13 14 | jca | ⊢ ( 𝜑  →  ( 𝑌  ∈  ( 𝐴 𝐼 𝐶 )  ∧  ( 𝑌  =  𝐵  ∨  𝑌 ( 𝐾 ‘ 𝐵 ) 𝑋 ) ) ) | 
						
							| 25 | 9 23 24 | rspcedvd | ⊢ ( 𝜑  →  ∃ 𝑥  ∈  𝑃 ( 𝑥  ∈  ( 𝐴 𝐼 𝐶 )  ∧  ( 𝑥  =  𝐵  ∨  𝑥 ( 𝐾 ‘ 𝐵 ) 𝑋 ) ) ) | 
						
							| 26 | 15 25 | jca | ⊢ ( 𝜑  →  ( ( 𝐴  ≠  𝐵  ∧  𝐶  ≠  𝐵  ∧  𝑋  ≠  𝐵 )  ∧  ∃ 𝑥  ∈  𝑃 ( 𝑥  ∈  ( 𝐴 𝐼 𝐶 )  ∧  ( 𝑥  =  𝐵  ∨  𝑥 ( 𝐾 ‘ 𝐵 ) 𝑋 ) ) ) ) | 
						
							| 27 | 1 2 3 4 5 6 7 8 | isinag | ⊢ ( 𝜑  →  ( 𝑋 ( inA ‘ 𝐺 ) 〈“ 𝐴 𝐵 𝐶 ”〉  ↔  ( ( 𝐴  ≠  𝐵  ∧  𝐶  ≠  𝐵  ∧  𝑋  ≠  𝐵 )  ∧  ∃ 𝑥  ∈  𝑃 ( 𝑥  ∈  ( 𝐴 𝐼 𝐶 )  ∧  ( 𝑥  =  𝐵  ∨  𝑥 ( 𝐾 ‘ 𝐵 ) 𝑋 ) ) ) ) ) | 
						
							| 28 | 26 27 | mpbird | ⊢ ( 𝜑  →  𝑋 ( inA ‘ 𝐺 ) 〈“ 𝐴 𝐵 𝐶 ”〉 ) |