| Step | Hyp | Ref | Expression | 
						
							| 1 |  | mrccss.v | ⊢ 𝑉  =  ( Base ‘ 𝑊 ) | 
						
							| 2 |  | mrccss.o | ⊢  ⊥   =  ( ocv ‘ 𝑊 ) | 
						
							| 3 |  | mrccss.c | ⊢ 𝐶  =  ( ClSubSp ‘ 𝑊 ) | 
						
							| 4 |  | mrccss.f | ⊢ 𝐹  =  ( mrCls ‘ 𝐶 ) | 
						
							| 5 | 1 3 | cssmre | ⊢ ( 𝑊  ∈  PreHil  →  𝐶  ∈  ( Moore ‘ 𝑉 ) ) | 
						
							| 6 | 5 | adantr | ⊢ ( ( 𝑊  ∈  PreHil  ∧  𝑆  ⊆  𝑉 )  →  𝐶  ∈  ( Moore ‘ 𝑉 ) ) | 
						
							| 7 | 1 2 | ocvocv | ⊢ ( ( 𝑊  ∈  PreHil  ∧  𝑆  ⊆  𝑉 )  →  𝑆  ⊆  (  ⊥  ‘ (  ⊥  ‘ 𝑆 ) ) ) | 
						
							| 8 | 1 2 | ocvss | ⊢ (  ⊥  ‘ 𝑆 )  ⊆  𝑉 | 
						
							| 9 | 8 | a1i | ⊢ ( 𝑆  ⊆  𝑉  →  (  ⊥  ‘ 𝑆 )  ⊆  𝑉 ) | 
						
							| 10 | 1 3 2 | ocvcss | ⊢ ( ( 𝑊  ∈  PreHil  ∧  (  ⊥  ‘ 𝑆 )  ⊆  𝑉 )  →  (  ⊥  ‘ (  ⊥  ‘ 𝑆 ) )  ∈  𝐶 ) | 
						
							| 11 | 9 10 | sylan2 | ⊢ ( ( 𝑊  ∈  PreHil  ∧  𝑆  ⊆  𝑉 )  →  (  ⊥  ‘ (  ⊥  ‘ 𝑆 ) )  ∈  𝐶 ) | 
						
							| 12 | 4 | mrcsscl | ⊢ ( ( 𝐶  ∈  ( Moore ‘ 𝑉 )  ∧  𝑆  ⊆  (  ⊥  ‘ (  ⊥  ‘ 𝑆 ) )  ∧  (  ⊥  ‘ (  ⊥  ‘ 𝑆 ) )  ∈  𝐶 )  →  ( 𝐹 ‘ 𝑆 )  ⊆  (  ⊥  ‘ (  ⊥  ‘ 𝑆 ) ) ) | 
						
							| 13 | 6 7 11 12 | syl3anc | ⊢ ( ( 𝑊  ∈  PreHil  ∧  𝑆  ⊆  𝑉 )  →  ( 𝐹 ‘ 𝑆 )  ⊆  (  ⊥  ‘ (  ⊥  ‘ 𝑆 ) ) ) | 
						
							| 14 | 4 | mrcssid | ⊢ ( ( 𝐶  ∈  ( Moore ‘ 𝑉 )  ∧  𝑆  ⊆  𝑉 )  →  𝑆  ⊆  ( 𝐹 ‘ 𝑆 ) ) | 
						
							| 15 | 5 14 | sylan | ⊢ ( ( 𝑊  ∈  PreHil  ∧  𝑆  ⊆  𝑉 )  →  𝑆  ⊆  ( 𝐹 ‘ 𝑆 ) ) | 
						
							| 16 | 2 | ocv2ss | ⊢ ( 𝑆  ⊆  ( 𝐹 ‘ 𝑆 )  →  (  ⊥  ‘ ( 𝐹 ‘ 𝑆 ) )  ⊆  (  ⊥  ‘ 𝑆 ) ) | 
						
							| 17 | 2 | ocv2ss | ⊢ ( (  ⊥  ‘ ( 𝐹 ‘ 𝑆 ) )  ⊆  (  ⊥  ‘ 𝑆 )  →  (  ⊥  ‘ (  ⊥  ‘ 𝑆 ) )  ⊆  (  ⊥  ‘ (  ⊥  ‘ ( 𝐹 ‘ 𝑆 ) ) ) ) | 
						
							| 18 | 15 16 17 | 3syl | ⊢ ( ( 𝑊  ∈  PreHil  ∧  𝑆  ⊆  𝑉 )  →  (  ⊥  ‘ (  ⊥  ‘ 𝑆 ) )  ⊆  (  ⊥  ‘ (  ⊥  ‘ ( 𝐹 ‘ 𝑆 ) ) ) ) | 
						
							| 19 | 4 | mrccl | ⊢ ( ( 𝐶  ∈  ( Moore ‘ 𝑉 )  ∧  𝑆  ⊆  𝑉 )  →  ( 𝐹 ‘ 𝑆 )  ∈  𝐶 ) | 
						
							| 20 | 5 19 | sylan | ⊢ ( ( 𝑊  ∈  PreHil  ∧  𝑆  ⊆  𝑉 )  →  ( 𝐹 ‘ 𝑆 )  ∈  𝐶 ) | 
						
							| 21 | 2 3 | cssi | ⊢ ( ( 𝐹 ‘ 𝑆 )  ∈  𝐶  →  ( 𝐹 ‘ 𝑆 )  =  (  ⊥  ‘ (  ⊥  ‘ ( 𝐹 ‘ 𝑆 ) ) ) ) | 
						
							| 22 | 20 21 | syl | ⊢ ( ( 𝑊  ∈  PreHil  ∧  𝑆  ⊆  𝑉 )  →  ( 𝐹 ‘ 𝑆 )  =  (  ⊥  ‘ (  ⊥  ‘ ( 𝐹 ‘ 𝑆 ) ) ) ) | 
						
							| 23 | 18 22 | sseqtrrd | ⊢ ( ( 𝑊  ∈  PreHil  ∧  𝑆  ⊆  𝑉 )  →  (  ⊥  ‘ (  ⊥  ‘ 𝑆 ) )  ⊆  ( 𝐹 ‘ 𝑆 ) ) | 
						
							| 24 | 13 23 | eqssd | ⊢ ( ( 𝑊  ∈  PreHil  ∧  𝑆  ⊆  𝑉 )  →  ( 𝐹 ‘ 𝑆 )  =  (  ⊥  ‘ (  ⊥  ‘ 𝑆 ) ) ) |