| Step | Hyp | Ref | Expression | 
						
							| 1 |  | djaval.h | ⊢ 𝐻  =  ( LHyp ‘ 𝐾 ) | 
						
							| 2 |  | djaval.t | ⊢ 𝑇  =  ( ( LTrn ‘ 𝐾 ) ‘ 𝑊 ) | 
						
							| 3 |  | djaval.i | ⊢ 𝐼  =  ( ( DIsoA ‘ 𝐾 ) ‘ 𝑊 ) | 
						
							| 4 |  | djaval.n | ⊢  ⊥   =  ( ( ocA ‘ 𝐾 ) ‘ 𝑊 ) | 
						
							| 5 |  | djaval.j | ⊢ 𝐽  =  ( ( vA ‘ 𝐾 ) ‘ 𝑊 ) | 
						
							| 6 | 1 2 3 4 5 | djafvalN | ⊢ ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  →  𝐽  =  ( 𝑥  ∈  𝒫  𝑇 ,  𝑦  ∈  𝒫  𝑇  ↦  (  ⊥  ‘ ( (  ⊥  ‘ 𝑥 )  ∩  (  ⊥  ‘ 𝑦 ) ) ) ) ) | 
						
							| 7 | 6 | adantr | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  ( 𝑋  ⊆  𝑇  ∧  𝑌  ⊆  𝑇 ) )  →  𝐽  =  ( 𝑥  ∈  𝒫  𝑇 ,  𝑦  ∈  𝒫  𝑇  ↦  (  ⊥  ‘ ( (  ⊥  ‘ 𝑥 )  ∩  (  ⊥  ‘ 𝑦 ) ) ) ) ) | 
						
							| 8 | 7 | oveqd | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  ( 𝑋  ⊆  𝑇  ∧  𝑌  ⊆  𝑇 ) )  →  ( 𝑋 𝐽 𝑌 )  =  ( 𝑋 ( 𝑥  ∈  𝒫  𝑇 ,  𝑦  ∈  𝒫  𝑇  ↦  (  ⊥  ‘ ( (  ⊥  ‘ 𝑥 )  ∩  (  ⊥  ‘ 𝑦 ) ) ) ) 𝑌 ) ) | 
						
							| 9 | 2 | fvexi | ⊢ 𝑇  ∈  V | 
						
							| 10 | 9 | elpw2 | ⊢ ( 𝑋  ∈  𝒫  𝑇  ↔  𝑋  ⊆  𝑇 ) | 
						
							| 11 | 10 | biimpri | ⊢ ( 𝑋  ⊆  𝑇  →  𝑋  ∈  𝒫  𝑇 ) | 
						
							| 12 | 11 | ad2antrl | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  ( 𝑋  ⊆  𝑇  ∧  𝑌  ⊆  𝑇 ) )  →  𝑋  ∈  𝒫  𝑇 ) | 
						
							| 13 | 9 | elpw2 | ⊢ ( 𝑌  ∈  𝒫  𝑇  ↔  𝑌  ⊆  𝑇 ) | 
						
							| 14 | 13 | biimpri | ⊢ ( 𝑌  ⊆  𝑇  →  𝑌  ∈  𝒫  𝑇 ) | 
						
							| 15 | 14 | ad2antll | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  ( 𝑋  ⊆  𝑇  ∧  𝑌  ⊆  𝑇 ) )  →  𝑌  ∈  𝒫  𝑇 ) | 
						
							| 16 |  | fvexd | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  ( 𝑋  ⊆  𝑇  ∧  𝑌  ⊆  𝑇 ) )  →  (  ⊥  ‘ ( (  ⊥  ‘ 𝑋 )  ∩  (  ⊥  ‘ 𝑌 ) ) )  ∈  V ) | 
						
							| 17 |  | fveq2 | ⊢ ( 𝑥  =  𝑋  →  (  ⊥  ‘ 𝑥 )  =  (  ⊥  ‘ 𝑋 ) ) | 
						
							| 18 | 17 | ineq1d | ⊢ ( 𝑥  =  𝑋  →  ( (  ⊥  ‘ 𝑥 )  ∩  (  ⊥  ‘ 𝑦 ) )  =  ( (  ⊥  ‘ 𝑋 )  ∩  (  ⊥  ‘ 𝑦 ) ) ) | 
						
							| 19 | 18 | fveq2d | ⊢ ( 𝑥  =  𝑋  →  (  ⊥  ‘ ( (  ⊥  ‘ 𝑥 )  ∩  (  ⊥  ‘ 𝑦 ) ) )  =  (  ⊥  ‘ ( (  ⊥  ‘ 𝑋 )  ∩  (  ⊥  ‘ 𝑦 ) ) ) ) | 
						
							| 20 |  | fveq2 | ⊢ ( 𝑦  =  𝑌  →  (  ⊥  ‘ 𝑦 )  =  (  ⊥  ‘ 𝑌 ) ) | 
						
							| 21 | 20 | ineq2d | ⊢ ( 𝑦  =  𝑌  →  ( (  ⊥  ‘ 𝑋 )  ∩  (  ⊥  ‘ 𝑦 ) )  =  ( (  ⊥  ‘ 𝑋 )  ∩  (  ⊥  ‘ 𝑌 ) ) ) | 
						
							| 22 | 21 | fveq2d | ⊢ ( 𝑦  =  𝑌  →  (  ⊥  ‘ ( (  ⊥  ‘ 𝑋 )  ∩  (  ⊥  ‘ 𝑦 ) ) )  =  (  ⊥  ‘ ( (  ⊥  ‘ 𝑋 )  ∩  (  ⊥  ‘ 𝑌 ) ) ) ) | 
						
							| 23 |  | eqid | ⊢ ( 𝑥  ∈  𝒫  𝑇 ,  𝑦  ∈  𝒫  𝑇  ↦  (  ⊥  ‘ ( (  ⊥  ‘ 𝑥 )  ∩  (  ⊥  ‘ 𝑦 ) ) ) )  =  ( 𝑥  ∈  𝒫  𝑇 ,  𝑦  ∈  𝒫  𝑇  ↦  (  ⊥  ‘ ( (  ⊥  ‘ 𝑥 )  ∩  (  ⊥  ‘ 𝑦 ) ) ) ) | 
						
							| 24 | 19 22 23 | ovmpog | ⊢ ( ( 𝑋  ∈  𝒫  𝑇  ∧  𝑌  ∈  𝒫  𝑇  ∧  (  ⊥  ‘ ( (  ⊥  ‘ 𝑋 )  ∩  (  ⊥  ‘ 𝑌 ) ) )  ∈  V )  →  ( 𝑋 ( 𝑥  ∈  𝒫  𝑇 ,  𝑦  ∈  𝒫  𝑇  ↦  (  ⊥  ‘ ( (  ⊥  ‘ 𝑥 )  ∩  (  ⊥  ‘ 𝑦 ) ) ) ) 𝑌 )  =  (  ⊥  ‘ ( (  ⊥  ‘ 𝑋 )  ∩  (  ⊥  ‘ 𝑌 ) ) ) ) | 
						
							| 25 | 12 15 16 24 | syl3anc | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  ( 𝑋  ⊆  𝑇  ∧  𝑌  ⊆  𝑇 ) )  →  ( 𝑋 ( 𝑥  ∈  𝒫  𝑇 ,  𝑦  ∈  𝒫  𝑇  ↦  (  ⊥  ‘ ( (  ⊥  ‘ 𝑥 )  ∩  (  ⊥  ‘ 𝑦 ) ) ) ) 𝑌 )  =  (  ⊥  ‘ ( (  ⊥  ‘ 𝑋 )  ∩  (  ⊥  ‘ 𝑌 ) ) ) ) | 
						
							| 26 | 8 25 | eqtrd | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  ( 𝑋  ⊆  𝑇  ∧  𝑌  ⊆  𝑇 ) )  →  ( 𝑋 𝐽 𝑌 )  =  (  ⊥  ‘ ( (  ⊥  ‘ 𝑋 )  ∩  (  ⊥  ‘ 𝑌 ) ) ) ) |