| Step | 
						Hyp | 
						Ref | 
						Expression | 
					
						
							| 1 | 
							
								
							 | 
							olm1.b | 
							⊢ 𝐵  =  ( Base ‘ 𝐾 )  | 
						
						
							| 2 | 
							
								
							 | 
							olm1.m | 
							⊢  ∧   =  ( meet ‘ 𝐾 )  | 
						
						
							| 3 | 
							
								
							 | 
							olm1.u | 
							⊢  1   =  ( 1. ‘ 𝐾 )  | 
						
						
							| 4 | 
							
								
							 | 
							olop | 
							⊢ ( 𝐾  ∈  OL  →  𝐾  ∈  OP )  | 
						
						
							| 5 | 
							
								4
							 | 
							adantr | 
							⊢ ( ( 𝐾  ∈  OL  ∧  𝑋  ∈  𝐵 )  →  𝐾  ∈  OP )  | 
						
						
							| 6 | 
							
								
							 | 
							eqid | 
							⊢ ( 0. ‘ 𝐾 )  =  ( 0. ‘ 𝐾 )  | 
						
						
							| 7 | 
							
								
							 | 
							eqid | 
							⊢ ( oc ‘ 𝐾 )  =  ( oc ‘ 𝐾 )  | 
						
						
							| 8 | 
							
								6 3 7
							 | 
							opoc1 | 
							⊢ ( 𝐾  ∈  OP  →  ( ( oc ‘ 𝐾 ) ‘  1  )  =  ( 0. ‘ 𝐾 ) )  | 
						
						
							| 9 | 
							
								5 8
							 | 
							syl | 
							⊢ ( ( 𝐾  ∈  OL  ∧  𝑋  ∈  𝐵 )  →  ( ( oc ‘ 𝐾 ) ‘  1  )  =  ( 0. ‘ 𝐾 ) )  | 
						
						
							| 10 | 
							
								9
							 | 
							oveq2d | 
							⊢ ( ( 𝐾  ∈  OL  ∧  𝑋  ∈  𝐵 )  →  ( ( ( oc ‘ 𝐾 ) ‘ 𝑋 ) ( join ‘ 𝐾 ) ( ( oc ‘ 𝐾 ) ‘  1  ) )  =  ( ( ( oc ‘ 𝐾 ) ‘ 𝑋 ) ( join ‘ 𝐾 ) ( 0. ‘ 𝐾 ) ) )  | 
						
						
							| 11 | 
							
								1 7
							 | 
							opoccl | 
							⊢ ( ( 𝐾  ∈  OP  ∧  𝑋  ∈  𝐵 )  →  ( ( oc ‘ 𝐾 ) ‘ 𝑋 )  ∈  𝐵 )  | 
						
						
							| 12 | 
							
								4 11
							 | 
							sylan | 
							⊢ ( ( 𝐾  ∈  OL  ∧  𝑋  ∈  𝐵 )  →  ( ( oc ‘ 𝐾 ) ‘ 𝑋 )  ∈  𝐵 )  | 
						
						
							| 13 | 
							
								
							 | 
							eqid | 
							⊢ ( join ‘ 𝐾 )  =  ( join ‘ 𝐾 )  | 
						
						
							| 14 | 
							
								1 13 6
							 | 
							olj01 | 
							⊢ ( ( 𝐾  ∈  OL  ∧  ( ( oc ‘ 𝐾 ) ‘ 𝑋 )  ∈  𝐵 )  →  ( ( ( oc ‘ 𝐾 ) ‘ 𝑋 ) ( join ‘ 𝐾 ) ( 0. ‘ 𝐾 ) )  =  ( ( oc ‘ 𝐾 ) ‘ 𝑋 ) )  | 
						
						
							| 15 | 
							
								12 14
							 | 
							syldan | 
							⊢ ( ( 𝐾  ∈  OL  ∧  𝑋  ∈  𝐵 )  →  ( ( ( oc ‘ 𝐾 ) ‘ 𝑋 ) ( join ‘ 𝐾 ) ( 0. ‘ 𝐾 ) )  =  ( ( oc ‘ 𝐾 ) ‘ 𝑋 ) )  | 
						
						
							| 16 | 
							
								10 15
							 | 
							eqtrd | 
							⊢ ( ( 𝐾  ∈  OL  ∧  𝑋  ∈  𝐵 )  →  ( ( ( oc ‘ 𝐾 ) ‘ 𝑋 ) ( join ‘ 𝐾 ) ( ( oc ‘ 𝐾 ) ‘  1  ) )  =  ( ( oc ‘ 𝐾 ) ‘ 𝑋 ) )  | 
						
						
							| 17 | 
							
								16
							 | 
							fveq2d | 
							⊢ ( ( 𝐾  ∈  OL  ∧  𝑋  ∈  𝐵 )  →  ( ( oc ‘ 𝐾 ) ‘ ( ( ( oc ‘ 𝐾 ) ‘ 𝑋 ) ( join ‘ 𝐾 ) ( ( oc ‘ 𝐾 ) ‘  1  ) ) )  =  ( ( oc ‘ 𝐾 ) ‘ ( ( oc ‘ 𝐾 ) ‘ 𝑋 ) ) )  | 
						
						
							| 18 | 
							
								1 3
							 | 
							op1cl | 
							⊢ ( 𝐾  ∈  OP  →   1   ∈  𝐵 )  | 
						
						
							| 19 | 
							
								5 18
							 | 
							syl | 
							⊢ ( ( 𝐾  ∈  OL  ∧  𝑋  ∈  𝐵 )  →   1   ∈  𝐵 )  | 
						
						
							| 20 | 
							
								1 13 2 7
							 | 
							oldmj4 | 
							⊢ ( ( 𝐾  ∈  OL  ∧  𝑋  ∈  𝐵  ∧   1   ∈  𝐵 )  →  ( ( oc ‘ 𝐾 ) ‘ ( ( ( oc ‘ 𝐾 ) ‘ 𝑋 ) ( join ‘ 𝐾 ) ( ( oc ‘ 𝐾 ) ‘  1  ) ) )  =  ( 𝑋  ∧   1  ) )  | 
						
						
							| 21 | 
							
								19 20
							 | 
							mpd3an3 | 
							⊢ ( ( 𝐾  ∈  OL  ∧  𝑋  ∈  𝐵 )  →  ( ( oc ‘ 𝐾 ) ‘ ( ( ( oc ‘ 𝐾 ) ‘ 𝑋 ) ( join ‘ 𝐾 ) ( ( oc ‘ 𝐾 ) ‘  1  ) ) )  =  ( 𝑋  ∧   1  ) )  | 
						
						
							| 22 | 
							
								1 7
							 | 
							opococ | 
							⊢ ( ( 𝐾  ∈  OP  ∧  𝑋  ∈  𝐵 )  →  ( ( oc ‘ 𝐾 ) ‘ ( ( oc ‘ 𝐾 ) ‘ 𝑋 ) )  =  𝑋 )  | 
						
						
							| 23 | 
							
								4 22
							 | 
							sylan | 
							⊢ ( ( 𝐾  ∈  OL  ∧  𝑋  ∈  𝐵 )  →  ( ( oc ‘ 𝐾 ) ‘ ( ( oc ‘ 𝐾 ) ‘ 𝑋 ) )  =  𝑋 )  | 
						
						
							| 24 | 
							
								17 21 23
							 | 
							3eqtr3d | 
							⊢ ( ( 𝐾  ∈  OL  ∧  𝑋  ∈  𝐵 )  →  ( 𝑋  ∧   1  )  =  𝑋 )  |