| Step | Hyp | Ref | Expression | 
						
							| 1 |  | addsdilem4.1 |  |-  ( ph -> A e. No ) | 
						
							| 2 |  | addsdilem4.2 |  |-  ( ph -> B e. No ) | 
						
							| 3 |  | addsdilem4.3 |  |-  ( ph -> C e. No ) | 
						
							| 4 |  | addsdilem4.4 |  |-  ( ph -> A. xO e. ( ( _Left ` A ) u. ( _Right ` A ) ) ( xO x.s ( B +s C ) ) = ( ( xO x.s B ) +s ( xO x.s C ) ) ) | 
						
							| 5 |  | addsdilem4.5 |  |-  ( ph -> A. zO e. ( ( _Left ` C ) u. ( _Right ` C ) ) ( A x.s ( B +s zO ) ) = ( ( A x.s B ) +s ( A x.s zO ) ) ) | 
						
							| 6 |  | addsdilem4.6 |  |-  ( ph -> A. xO e. ( ( _Left ` A ) u. ( _Right ` A ) ) A. zO e. ( ( _Left ` C ) u. ( _Right ` C ) ) ( xO x.s ( B +s zO ) ) = ( ( xO x.s B ) +s ( xO x.s zO ) ) ) | 
						
							| 7 |  | addsdilem4.7 |  |-  ( ps -> X e. ( ( _Left ` A ) u. ( _Right ` A ) ) ) | 
						
							| 8 |  | addsdilem4.8 |  |-  ( ps -> Z e. ( ( _Left ` C ) u. ( _Right ` C ) ) ) | 
						
							| 9 |  | oveq1 |  |-  ( xO = X -> ( xO x.s ( B +s C ) ) = ( X x.s ( B +s C ) ) ) | 
						
							| 10 |  | oveq1 |  |-  ( xO = X -> ( xO x.s B ) = ( X x.s B ) ) | 
						
							| 11 |  | oveq1 |  |-  ( xO = X -> ( xO x.s C ) = ( X x.s C ) ) | 
						
							| 12 | 10 11 | oveq12d |  |-  ( xO = X -> ( ( xO x.s B ) +s ( xO x.s C ) ) = ( ( X x.s B ) +s ( X x.s C ) ) ) | 
						
							| 13 | 9 12 | eqeq12d |  |-  ( xO = X -> ( ( xO x.s ( B +s C ) ) = ( ( xO x.s B ) +s ( xO x.s C ) ) <-> ( X x.s ( B +s C ) ) = ( ( X x.s B ) +s ( X x.s C ) ) ) ) | 
						
							| 14 | 4 | adantr |  |-  ( ( ph /\ ps ) -> A. xO e. ( ( _Left ` A ) u. ( _Right ` A ) ) ( xO x.s ( B +s C ) ) = ( ( xO x.s B ) +s ( xO x.s C ) ) ) | 
						
							| 15 | 7 | adantl |  |-  ( ( ph /\ ps ) -> X e. ( ( _Left ` A ) u. ( _Right ` A ) ) ) | 
						
							| 16 | 13 14 15 | rspcdva |  |-  ( ( ph /\ ps ) -> ( X x.s ( B +s C ) ) = ( ( X x.s B ) +s ( X x.s C ) ) ) | 
						
							| 17 |  | oveq2 |  |-  ( zO = Z -> ( B +s zO ) = ( B +s Z ) ) | 
						
							| 18 | 17 | oveq2d |  |-  ( zO = Z -> ( A x.s ( B +s zO ) ) = ( A x.s ( B +s Z ) ) ) | 
						
							| 19 |  | oveq2 |  |-  ( zO = Z -> ( A x.s zO ) = ( A x.s Z ) ) | 
						
							| 20 | 19 | oveq2d |  |-  ( zO = Z -> ( ( A x.s B ) +s ( A x.s zO ) ) = ( ( A x.s B ) +s ( A x.s Z ) ) ) | 
						
							| 21 | 18 20 | eqeq12d |  |-  ( zO = Z -> ( ( A x.s ( B +s zO ) ) = ( ( A x.s B ) +s ( A x.s zO ) ) <-> ( A x.s ( B +s Z ) ) = ( ( A x.s B ) +s ( A x.s Z ) ) ) ) | 
						
							| 22 | 5 | adantr |  |-  ( ( ph /\ ps ) -> A. zO e. ( ( _Left ` C ) u. ( _Right ` C ) ) ( A x.s ( B +s zO ) ) = ( ( A x.s B ) +s ( A x.s zO ) ) ) | 
						
							| 23 | 8 | adantl |  |-  ( ( ph /\ ps ) -> Z e. ( ( _Left ` C ) u. ( _Right ` C ) ) ) | 
						
							| 24 | 21 22 23 | rspcdva |  |-  ( ( ph /\ ps ) -> ( A x.s ( B +s Z ) ) = ( ( A x.s B ) +s ( A x.s Z ) ) ) | 
						
							| 25 | 16 24 | oveq12d |  |-  ( ( ph /\ ps ) -> ( ( X x.s ( B +s C ) ) +s ( A x.s ( B +s Z ) ) ) = ( ( ( X x.s B ) +s ( X x.s C ) ) +s ( ( A x.s B ) +s ( A x.s Z ) ) ) ) | 
						
							| 26 |  | oveq1 |  |-  ( xO = X -> ( xO x.s ( B +s zO ) ) = ( X x.s ( B +s zO ) ) ) | 
						
							| 27 |  | oveq1 |  |-  ( xO = X -> ( xO x.s zO ) = ( X x.s zO ) ) | 
						
							| 28 | 10 27 | oveq12d |  |-  ( xO = X -> ( ( xO x.s B ) +s ( xO x.s zO ) ) = ( ( X x.s B ) +s ( X x.s zO ) ) ) | 
						
							| 29 | 26 28 | eqeq12d |  |-  ( xO = X -> ( ( xO x.s ( B +s zO ) ) = ( ( xO x.s B ) +s ( xO x.s zO ) ) <-> ( X x.s ( B +s zO ) ) = ( ( X x.s B ) +s ( X x.s zO ) ) ) ) | 
						
							| 30 | 17 | oveq2d |  |-  ( zO = Z -> ( X x.s ( B +s zO ) ) = ( X x.s ( B +s Z ) ) ) | 
						
							| 31 |  | oveq2 |  |-  ( zO = Z -> ( X x.s zO ) = ( X x.s Z ) ) | 
						
							| 32 | 31 | oveq2d |  |-  ( zO = Z -> ( ( X x.s B ) +s ( X x.s zO ) ) = ( ( X x.s B ) +s ( X x.s Z ) ) ) | 
						
							| 33 | 30 32 | eqeq12d |  |-  ( zO = Z -> ( ( X x.s ( B +s zO ) ) = ( ( X x.s B ) +s ( X x.s zO ) ) <-> ( X x.s ( B +s Z ) ) = ( ( X x.s B ) +s ( X x.s Z ) ) ) ) | 
						
							| 34 | 6 | adantr |  |-  ( ( ph /\ ps ) -> A. xO e. ( ( _Left ` A ) u. ( _Right ` A ) ) A. zO e. ( ( _Left ` C ) u. ( _Right ` C ) ) ( xO x.s ( B +s zO ) ) = ( ( xO x.s B ) +s ( xO x.s zO ) ) ) | 
						
							| 35 | 29 33 34 15 23 | rspc2dv |  |-  ( ( ph /\ ps ) -> ( X x.s ( B +s Z ) ) = ( ( X x.s B ) +s ( X x.s Z ) ) ) | 
						
							| 36 | 25 35 | oveq12d |  |-  ( ( ph /\ ps ) -> ( ( ( X x.s ( B +s C ) ) +s ( A x.s ( B +s Z ) ) ) -s ( X x.s ( B +s Z ) ) ) = ( ( ( ( X x.s B ) +s ( X x.s C ) ) +s ( ( A x.s B ) +s ( A x.s Z ) ) ) -s ( ( X x.s B ) +s ( X x.s Z ) ) ) ) | 
						
							| 37 |  | leftssno |  |-  ( _Left ` A ) C_ No | 
						
							| 38 |  | rightssno |  |-  ( _Right ` A ) C_ No | 
						
							| 39 | 37 38 | unssi |  |-  ( ( _Left ` A ) u. ( _Right ` A ) ) C_ No | 
						
							| 40 | 39 7 | sselid |  |-  ( ps -> X e. No ) | 
						
							| 41 | 40 | adantl |  |-  ( ( ph /\ ps ) -> X e. No ) | 
						
							| 42 | 2 | adantr |  |-  ( ( ph /\ ps ) -> B e. No ) | 
						
							| 43 | 41 42 | mulscld |  |-  ( ( ph /\ ps ) -> ( X x.s B ) e. No ) | 
						
							| 44 | 3 | adantr |  |-  ( ( ph /\ ps ) -> C e. No ) | 
						
							| 45 | 41 44 | mulscld |  |-  ( ( ph /\ ps ) -> ( X x.s C ) e. No ) | 
						
							| 46 | 43 45 | addscld |  |-  ( ( ph /\ ps ) -> ( ( X x.s B ) +s ( X x.s C ) ) e. No ) | 
						
							| 47 | 1 2 | mulscld |  |-  ( ph -> ( A x.s B ) e. No ) | 
						
							| 48 | 47 | adantr |  |-  ( ( ph /\ ps ) -> ( A x.s B ) e. No ) | 
						
							| 49 | 1 | adantr |  |-  ( ( ph /\ ps ) -> A e. No ) | 
						
							| 50 |  | leftssno |  |-  ( _Left ` C ) C_ No | 
						
							| 51 |  | rightssno |  |-  ( _Right ` C ) C_ No | 
						
							| 52 | 50 51 | unssi |  |-  ( ( _Left ` C ) u. ( _Right ` C ) ) C_ No | 
						
							| 53 | 52 8 | sselid |  |-  ( ps -> Z e. No ) | 
						
							| 54 | 53 | adantl |  |-  ( ( ph /\ ps ) -> Z e. No ) | 
						
							| 55 | 49 54 | mulscld |  |-  ( ( ph /\ ps ) -> ( A x.s Z ) e. No ) | 
						
							| 56 | 48 55 | addscld |  |-  ( ( ph /\ ps ) -> ( ( A x.s B ) +s ( A x.s Z ) ) e. No ) | 
						
							| 57 | 46 56 | addscld |  |-  ( ( ph /\ ps ) -> ( ( ( X x.s B ) +s ( X x.s C ) ) +s ( ( A x.s B ) +s ( A x.s Z ) ) ) e. No ) | 
						
							| 58 | 41 54 | mulscld |  |-  ( ( ph /\ ps ) -> ( X x.s Z ) e. No ) | 
						
							| 59 | 57 43 58 | subsubs4d |  |-  ( ( ph /\ ps ) -> ( ( ( ( ( X x.s B ) +s ( X x.s C ) ) +s ( ( A x.s B ) +s ( A x.s Z ) ) ) -s ( X x.s B ) ) -s ( X x.s Z ) ) = ( ( ( ( X x.s B ) +s ( X x.s C ) ) +s ( ( A x.s B ) +s ( A x.s Z ) ) ) -s ( ( X x.s B ) +s ( X x.s Z ) ) ) ) | 
						
							| 60 | 46 56 43 | addsubsd |  |-  ( ( ph /\ ps ) -> ( ( ( ( X x.s B ) +s ( X x.s C ) ) +s ( ( A x.s B ) +s ( A x.s Z ) ) ) -s ( X x.s B ) ) = ( ( ( ( X x.s B ) +s ( X x.s C ) ) -s ( X x.s B ) ) +s ( ( A x.s B ) +s ( A x.s Z ) ) ) ) | 
						
							| 61 | 43 45 | addscomd |  |-  ( ( ph /\ ps ) -> ( ( X x.s B ) +s ( X x.s C ) ) = ( ( X x.s C ) +s ( X x.s B ) ) ) | 
						
							| 62 | 61 | oveq1d |  |-  ( ( ph /\ ps ) -> ( ( ( X x.s B ) +s ( X x.s C ) ) -s ( X x.s B ) ) = ( ( ( X x.s C ) +s ( X x.s B ) ) -s ( X x.s B ) ) ) | 
						
							| 63 |  | pncans |  |-  ( ( ( X x.s C ) e. No /\ ( X x.s B ) e. No ) -> ( ( ( X x.s C ) +s ( X x.s B ) ) -s ( X x.s B ) ) = ( X x.s C ) ) | 
						
							| 64 | 45 43 63 | syl2anc |  |-  ( ( ph /\ ps ) -> ( ( ( X x.s C ) +s ( X x.s B ) ) -s ( X x.s B ) ) = ( X x.s C ) ) | 
						
							| 65 | 62 64 | eqtrd |  |-  ( ( ph /\ ps ) -> ( ( ( X x.s B ) +s ( X x.s C ) ) -s ( X x.s B ) ) = ( X x.s C ) ) | 
						
							| 66 | 65 | oveq1d |  |-  ( ( ph /\ ps ) -> ( ( ( ( X x.s B ) +s ( X x.s C ) ) -s ( X x.s B ) ) +s ( ( A x.s B ) +s ( A x.s Z ) ) ) = ( ( X x.s C ) +s ( ( A x.s B ) +s ( A x.s Z ) ) ) ) | 
						
							| 67 | 45 48 55 | adds12d |  |-  ( ( ph /\ ps ) -> ( ( X x.s C ) +s ( ( A x.s B ) +s ( A x.s Z ) ) ) = ( ( A x.s B ) +s ( ( X x.s C ) +s ( A x.s Z ) ) ) ) | 
						
							| 68 | 60 66 67 | 3eqtrd |  |-  ( ( ph /\ ps ) -> ( ( ( ( X x.s B ) +s ( X x.s C ) ) +s ( ( A x.s B ) +s ( A x.s Z ) ) ) -s ( X x.s B ) ) = ( ( A x.s B ) +s ( ( X x.s C ) +s ( A x.s Z ) ) ) ) | 
						
							| 69 | 68 | oveq1d |  |-  ( ( ph /\ ps ) -> ( ( ( ( ( X x.s B ) +s ( X x.s C ) ) +s ( ( A x.s B ) +s ( A x.s Z ) ) ) -s ( X x.s B ) ) -s ( X x.s Z ) ) = ( ( ( A x.s B ) +s ( ( X x.s C ) +s ( A x.s Z ) ) ) -s ( X x.s Z ) ) ) | 
						
							| 70 | 45 55 | addscld |  |-  ( ( ph /\ ps ) -> ( ( X x.s C ) +s ( A x.s Z ) ) e. No ) | 
						
							| 71 | 48 70 58 | addsubsassd |  |-  ( ( ph /\ ps ) -> ( ( ( A x.s B ) +s ( ( X x.s C ) +s ( A x.s Z ) ) ) -s ( X x.s Z ) ) = ( ( A x.s B ) +s ( ( ( X x.s C ) +s ( A x.s Z ) ) -s ( X x.s Z ) ) ) ) | 
						
							| 72 | 69 71 | eqtrd |  |-  ( ( ph /\ ps ) -> ( ( ( ( ( X x.s B ) +s ( X x.s C ) ) +s ( ( A x.s B ) +s ( A x.s Z ) ) ) -s ( X x.s B ) ) -s ( X x.s Z ) ) = ( ( A x.s B ) +s ( ( ( X x.s C ) +s ( A x.s Z ) ) -s ( X x.s Z ) ) ) ) | 
						
							| 73 | 36 59 72 | 3eqtr2d |  |-  ( ( ph /\ ps ) -> ( ( ( X x.s ( B +s C ) ) +s ( A x.s ( B +s Z ) ) ) -s ( X x.s ( B +s Z ) ) ) = ( ( A x.s B ) +s ( ( ( X x.s C ) +s ( A x.s Z ) ) -s ( X x.s Z ) ) ) ) |