| Step | Hyp | Ref | Expression | 
						
							| 1 |  | hstrlem3.1 |  |-  S = ( x e. CH |-> ( ( projh ` x ) ` u ) ) | 
						
							| 2 |  | hstrlem3.2 |  |-  ( ph <-> ( u e. ( A \ B ) /\ ( normh ` u ) = 1 ) ) | 
						
							| 3 |  | hstrlem3.3 |  |-  A e. CH | 
						
							| 4 |  | hstrlem3.4 |  |-  B e. CH | 
						
							| 5 | 1 | hstrlem2 |  |-  ( B e. CH -> ( S ` B ) = ( ( projh ` B ) ` u ) ) | 
						
							| 6 | 5 | fveq2d |  |-  ( B e. CH -> ( normh ` ( S ` B ) ) = ( normh ` ( ( projh ` B ) ` u ) ) ) | 
						
							| 7 | 4 6 | ax-mp |  |-  ( normh ` ( S ` B ) ) = ( normh ` ( ( projh ` B ) ` u ) ) | 
						
							| 8 |  | eldif |  |-  ( u e. ( A \ B ) <-> ( u e. A /\ -. u e. B ) ) | 
						
							| 9 | 3 | cheli |  |-  ( u e. A -> u e. ~H ) | 
						
							| 10 |  | pjnel |  |-  ( ( B e. CH /\ u e. ~H ) -> ( -. u e. B <-> ( normh ` ( ( projh ` B ) ` u ) ) < ( normh ` u ) ) ) | 
						
							| 11 | 4 10 | mpan |  |-  ( u e. ~H -> ( -. u e. B <-> ( normh ` ( ( projh ` B ) ` u ) ) < ( normh ` u ) ) ) | 
						
							| 12 | 11 | biimpa |  |-  ( ( u e. ~H /\ -. u e. B ) -> ( normh ` ( ( projh ` B ) ` u ) ) < ( normh ` u ) ) | 
						
							| 13 | 9 12 | sylan |  |-  ( ( u e. A /\ -. u e. B ) -> ( normh ` ( ( projh ` B ) ` u ) ) < ( normh ` u ) ) | 
						
							| 14 | 8 13 | sylbi |  |-  ( u e. ( A \ B ) -> ( normh ` ( ( projh ` B ) ` u ) ) < ( normh ` u ) ) | 
						
							| 15 |  | breq2 |  |-  ( ( normh ` u ) = 1 -> ( ( normh ` ( ( projh ` B ) ` u ) ) < ( normh ` u ) <-> ( normh ` ( ( projh ` B ) ` u ) ) < 1 ) ) | 
						
							| 16 | 14 15 | imbitrid |  |-  ( ( normh ` u ) = 1 -> ( u e. ( A \ B ) -> ( normh ` ( ( projh ` B ) ` u ) ) < 1 ) ) | 
						
							| 17 | 16 | impcom |  |-  ( ( u e. ( A \ B ) /\ ( normh ` u ) = 1 ) -> ( normh ` ( ( projh ` B ) ` u ) ) < 1 ) | 
						
							| 18 | 7 17 | eqbrtrid |  |-  ( ( u e. ( A \ B ) /\ ( normh ` u ) = 1 ) -> ( normh ` ( S ` B ) ) < 1 ) | 
						
							| 19 | 2 18 | sylbi |  |-  ( ph -> ( normh ` ( S ` B ) ) < 1 ) |