| Step | Hyp | Ref | Expression | 
						
							| 1 |  | eropr.1 |  |-  J = ( A /. R ) | 
						
							| 2 |  | eropr.2 |  |-  K = ( B /. S ) | 
						
							| 3 |  | eropr.3 |  |-  ( ph -> T e. Z ) | 
						
							| 4 |  | eropr.4 |  |-  ( ph -> R Er U ) | 
						
							| 5 |  | eropr.5 |  |-  ( ph -> S Er V ) | 
						
							| 6 |  | eropr.6 |  |-  ( ph -> T Er W ) | 
						
							| 7 |  | eropr.7 |  |-  ( ph -> A C_ U ) | 
						
							| 8 |  | eropr.8 |  |-  ( ph -> B C_ V ) | 
						
							| 9 |  | eropr.9 |  |-  ( ph -> C C_ W ) | 
						
							| 10 |  | eropr.10 |  |-  ( ph -> .+ : ( A X. B ) --> C ) | 
						
							| 11 |  | eropr.11 |  |-  ( ( ph /\ ( ( r e. A /\ s e. A ) /\ ( t e. B /\ u e. B ) ) ) -> ( ( r R s /\ t S u ) -> ( r .+ t ) T ( s .+ u ) ) ) | 
						
							| 12 |  | eropr.12 |  |-  .+^ = { <. <. x , y >. , z >. | E. p e. A E. q e. B ( ( x = [ p ] R /\ y = [ q ] S ) /\ z = [ ( p .+ q ) ] T ) } | 
						
							| 13 |  | eropr.13 |  |-  ( ph -> R e. X ) | 
						
							| 14 |  | eropr.14 |  |-  ( ph -> S e. Y ) | 
						
							| 15 | 1 2 3 4 5 6 7 8 9 10 11 12 | erovlem |  |-  ( ph -> .+^ = ( x e. J , y e. K |-> ( iota z E. p e. A E. q e. B ( ( x = [ p ] R /\ y = [ q ] S ) /\ z = [ ( p .+ q ) ] T ) ) ) ) | 
						
							| 16 | 15 | 3ad2ant1 |  |-  ( ( ph /\ P e. A /\ Q e. B ) -> .+^ = ( x e. J , y e. K |-> ( iota z E. p e. A E. q e. B ( ( x = [ p ] R /\ y = [ q ] S ) /\ z = [ ( p .+ q ) ] T ) ) ) ) | 
						
							| 17 |  | simprl |  |-  ( ( ( ph /\ P e. A /\ Q e. B ) /\ ( x = [ P ] R /\ y = [ Q ] S ) ) -> x = [ P ] R ) | 
						
							| 18 | 17 | eqeq1d |  |-  ( ( ( ph /\ P e. A /\ Q e. B ) /\ ( x = [ P ] R /\ y = [ Q ] S ) ) -> ( x = [ p ] R <-> [ P ] R = [ p ] R ) ) | 
						
							| 19 |  | simprr |  |-  ( ( ( ph /\ P e. A /\ Q e. B ) /\ ( x = [ P ] R /\ y = [ Q ] S ) ) -> y = [ Q ] S ) | 
						
							| 20 | 19 | eqeq1d |  |-  ( ( ( ph /\ P e. A /\ Q e. B ) /\ ( x = [ P ] R /\ y = [ Q ] S ) ) -> ( y = [ q ] S <-> [ Q ] S = [ q ] S ) ) | 
						
							| 21 | 18 20 | anbi12d |  |-  ( ( ( ph /\ P e. A /\ Q e. B ) /\ ( x = [ P ] R /\ y = [ Q ] S ) ) -> ( ( x = [ p ] R /\ y = [ q ] S ) <-> ( [ P ] R = [ p ] R /\ [ Q ] S = [ q ] S ) ) ) | 
						
							| 22 | 21 | anbi1d |  |-  ( ( ( ph /\ P e. A /\ Q e. B ) /\ ( x = [ P ] R /\ y = [ Q ] S ) ) -> ( ( ( x = [ p ] R /\ y = [ q ] S ) /\ z = [ ( p .+ q ) ] T ) <-> ( ( [ P ] R = [ p ] R /\ [ Q ] S = [ q ] S ) /\ z = [ ( p .+ q ) ] T ) ) ) | 
						
							| 23 | 22 | 2rexbidv |  |-  ( ( ( ph /\ P e. A /\ Q e. B ) /\ ( x = [ P ] R /\ y = [ Q ] S ) ) -> ( E. p e. A E. q e. B ( ( x = [ p ] R /\ y = [ q ] S ) /\ z = [ ( p .+ q ) ] T ) <-> E. p e. A E. q e. B ( ( [ P ] R = [ p ] R /\ [ Q ] S = [ q ] S ) /\ z = [ ( p .+ q ) ] T ) ) ) | 
						
							| 24 | 23 | iotabidv |  |-  ( ( ( ph /\ P e. A /\ Q e. B ) /\ ( x = [ P ] R /\ y = [ Q ] S ) ) -> ( iota z E. p e. A E. q e. B ( ( x = [ p ] R /\ y = [ q ] S ) /\ z = [ ( p .+ q ) ] T ) ) = ( iota z E. p e. A E. q e. B ( ( [ P ] R = [ p ] R /\ [ Q ] S = [ q ] S ) /\ z = [ ( p .+ q ) ] T ) ) ) | 
						
							| 25 |  | ecelqsg |  |-  ( ( R e. X /\ P e. A ) -> [ P ] R e. ( A /. R ) ) | 
						
							| 26 | 25 1 | eleqtrrdi |  |-  ( ( R e. X /\ P e. A ) -> [ P ] R e. J ) | 
						
							| 27 | 13 26 | sylan |  |-  ( ( ph /\ P e. A ) -> [ P ] R e. J ) | 
						
							| 28 | 27 | 3adant3 |  |-  ( ( ph /\ P e. A /\ Q e. B ) -> [ P ] R e. J ) | 
						
							| 29 |  | ecelqsg |  |-  ( ( S e. Y /\ Q e. B ) -> [ Q ] S e. ( B /. S ) ) | 
						
							| 30 | 29 2 | eleqtrrdi |  |-  ( ( S e. Y /\ Q e. B ) -> [ Q ] S e. K ) | 
						
							| 31 | 14 30 | sylan |  |-  ( ( ph /\ Q e. B ) -> [ Q ] S e. K ) | 
						
							| 32 | 31 | 3adant2 |  |-  ( ( ph /\ P e. A /\ Q e. B ) -> [ Q ] S e. K ) | 
						
							| 33 |  | iotaex |  |-  ( iota z E. p e. A E. q e. B ( ( [ P ] R = [ p ] R /\ [ Q ] S = [ q ] S ) /\ z = [ ( p .+ q ) ] T ) ) e. _V | 
						
							| 34 | 33 | a1i |  |-  ( ( ph /\ P e. A /\ Q e. B ) -> ( iota z E. p e. A E. q e. B ( ( [ P ] R = [ p ] R /\ [ Q ] S = [ q ] S ) /\ z = [ ( p .+ q ) ] T ) ) e. _V ) | 
						
							| 35 | 16 24 28 32 34 | ovmpod |  |-  ( ( ph /\ P e. A /\ Q e. B ) -> ( [ P ] R .+^ [ Q ] S ) = ( iota z E. p e. A E. q e. B ( ( [ P ] R = [ p ] R /\ [ Q ] S = [ q ] S ) /\ z = [ ( p .+ q ) ] T ) ) ) | 
						
							| 36 |  | eqid |  |-  [ P ] R = [ P ] R | 
						
							| 37 |  | eqid |  |-  [ Q ] S = [ Q ] S | 
						
							| 38 | 36 37 | pm3.2i |  |-  ( [ P ] R = [ P ] R /\ [ Q ] S = [ Q ] S ) | 
						
							| 39 |  | eqid |  |-  [ ( P .+ Q ) ] T = [ ( P .+ Q ) ] T | 
						
							| 40 | 38 39 | pm3.2i |  |-  ( ( [ P ] R = [ P ] R /\ [ Q ] S = [ Q ] S ) /\ [ ( P .+ Q ) ] T = [ ( P .+ Q ) ] T ) | 
						
							| 41 |  | eceq1 |  |-  ( p = P -> [ p ] R = [ P ] R ) | 
						
							| 42 | 41 | eqeq2d |  |-  ( p = P -> ( [ P ] R = [ p ] R <-> [ P ] R = [ P ] R ) ) | 
						
							| 43 | 42 | anbi1d |  |-  ( p = P -> ( ( [ P ] R = [ p ] R /\ [ Q ] S = [ q ] S ) <-> ( [ P ] R = [ P ] R /\ [ Q ] S = [ q ] S ) ) ) | 
						
							| 44 |  | oveq1 |  |-  ( p = P -> ( p .+ q ) = ( P .+ q ) ) | 
						
							| 45 | 44 | eceq1d |  |-  ( p = P -> [ ( p .+ q ) ] T = [ ( P .+ q ) ] T ) | 
						
							| 46 | 45 | eqeq2d |  |-  ( p = P -> ( [ ( P .+ Q ) ] T = [ ( p .+ q ) ] T <-> [ ( P .+ Q ) ] T = [ ( P .+ q ) ] T ) ) | 
						
							| 47 | 43 46 | anbi12d |  |-  ( p = P -> ( ( ( [ P ] R = [ p ] R /\ [ Q ] S = [ q ] S ) /\ [ ( P .+ Q ) ] T = [ ( p .+ q ) ] T ) <-> ( ( [ P ] R = [ P ] R /\ [ Q ] S = [ q ] S ) /\ [ ( P .+ Q ) ] T = [ ( P .+ q ) ] T ) ) ) | 
						
							| 48 |  | eceq1 |  |-  ( q = Q -> [ q ] S = [ Q ] S ) | 
						
							| 49 | 48 | eqeq2d |  |-  ( q = Q -> ( [ Q ] S = [ q ] S <-> [ Q ] S = [ Q ] S ) ) | 
						
							| 50 | 49 | anbi2d |  |-  ( q = Q -> ( ( [ P ] R = [ P ] R /\ [ Q ] S = [ q ] S ) <-> ( [ P ] R = [ P ] R /\ [ Q ] S = [ Q ] S ) ) ) | 
						
							| 51 |  | oveq2 |  |-  ( q = Q -> ( P .+ q ) = ( P .+ Q ) ) | 
						
							| 52 | 51 | eceq1d |  |-  ( q = Q -> [ ( P .+ q ) ] T = [ ( P .+ Q ) ] T ) | 
						
							| 53 | 52 | eqeq2d |  |-  ( q = Q -> ( [ ( P .+ Q ) ] T = [ ( P .+ q ) ] T <-> [ ( P .+ Q ) ] T = [ ( P .+ Q ) ] T ) ) | 
						
							| 54 | 50 53 | anbi12d |  |-  ( q = Q -> ( ( ( [ P ] R = [ P ] R /\ [ Q ] S = [ q ] S ) /\ [ ( P .+ Q ) ] T = [ ( P .+ q ) ] T ) <-> ( ( [ P ] R = [ P ] R /\ [ Q ] S = [ Q ] S ) /\ [ ( P .+ Q ) ] T = [ ( P .+ Q ) ] T ) ) ) | 
						
							| 55 | 47 54 | rspc2ev |  |-  ( ( P e. A /\ Q e. B /\ ( ( [ P ] R = [ P ] R /\ [ Q ] S = [ Q ] S ) /\ [ ( P .+ Q ) ] T = [ ( P .+ Q ) ] T ) ) -> E. p e. A E. q e. B ( ( [ P ] R = [ p ] R /\ [ Q ] S = [ q ] S ) /\ [ ( P .+ Q ) ] T = [ ( p .+ q ) ] T ) ) | 
						
							| 56 | 40 55 | mp3an3 |  |-  ( ( P e. A /\ Q e. B ) -> E. p e. A E. q e. B ( ( [ P ] R = [ p ] R /\ [ Q ] S = [ q ] S ) /\ [ ( P .+ Q ) ] T = [ ( p .+ q ) ] T ) ) | 
						
							| 57 | 56 | 3adant1 |  |-  ( ( ph /\ P e. A /\ Q e. B ) -> E. p e. A E. q e. B ( ( [ P ] R = [ p ] R /\ [ Q ] S = [ q ] S ) /\ [ ( P .+ Q ) ] T = [ ( p .+ q ) ] T ) ) | 
						
							| 58 |  | ecexg |  |-  ( T e. Z -> [ ( P .+ Q ) ] T e. _V ) | 
						
							| 59 | 3 58 | syl |  |-  ( ph -> [ ( P .+ Q ) ] T e. _V ) | 
						
							| 60 | 59 | 3ad2ant1 |  |-  ( ( ph /\ P e. A /\ Q e. B ) -> [ ( P .+ Q ) ] T e. _V ) | 
						
							| 61 |  | simp1 |  |-  ( ( ph /\ P e. A /\ Q e. B ) -> ph ) | 
						
							| 62 | 1 2 3 4 5 6 7 8 9 10 11 | eroveu |  |-  ( ( ph /\ ( [ P ] R e. J /\ [ Q ] S e. K ) ) -> E! z E. p e. A E. q e. B ( ( [ P ] R = [ p ] R /\ [ Q ] S = [ q ] S ) /\ z = [ ( p .+ q ) ] T ) ) | 
						
							| 63 | 61 28 32 62 | syl12anc |  |-  ( ( ph /\ P e. A /\ Q e. B ) -> E! z E. p e. A E. q e. B ( ( [ P ] R = [ p ] R /\ [ Q ] S = [ q ] S ) /\ z = [ ( p .+ q ) ] T ) ) | 
						
							| 64 |  | simpr |  |-  ( ( ( ph /\ P e. A /\ Q e. B ) /\ z = [ ( P .+ Q ) ] T ) -> z = [ ( P .+ Q ) ] T ) | 
						
							| 65 | 64 | eqeq1d |  |-  ( ( ( ph /\ P e. A /\ Q e. B ) /\ z = [ ( P .+ Q ) ] T ) -> ( z = [ ( p .+ q ) ] T <-> [ ( P .+ Q ) ] T = [ ( p .+ q ) ] T ) ) | 
						
							| 66 | 65 | anbi2d |  |-  ( ( ( ph /\ P e. A /\ Q e. B ) /\ z = [ ( P .+ Q ) ] T ) -> ( ( ( [ P ] R = [ p ] R /\ [ Q ] S = [ q ] S ) /\ z = [ ( p .+ q ) ] T ) <-> ( ( [ P ] R = [ p ] R /\ [ Q ] S = [ q ] S ) /\ [ ( P .+ Q ) ] T = [ ( p .+ q ) ] T ) ) ) | 
						
							| 67 | 66 | 2rexbidv |  |-  ( ( ( ph /\ P e. A /\ Q e. B ) /\ z = [ ( P .+ Q ) ] T ) -> ( E. p e. A E. q e. B ( ( [ P ] R = [ p ] R /\ [ Q ] S = [ q ] S ) /\ z = [ ( p .+ q ) ] T ) <-> E. p e. A E. q e. B ( ( [ P ] R = [ p ] R /\ [ Q ] S = [ q ] S ) /\ [ ( P .+ Q ) ] T = [ ( p .+ q ) ] T ) ) ) | 
						
							| 68 | 60 63 67 | iota2d |  |-  ( ( ph /\ P e. A /\ Q e. B ) -> ( E. p e. A E. q e. B ( ( [ P ] R = [ p ] R /\ [ Q ] S = [ q ] S ) /\ [ ( P .+ Q ) ] T = [ ( p .+ q ) ] T ) <-> ( iota z E. p e. A E. q e. B ( ( [ P ] R = [ p ] R /\ [ Q ] S = [ q ] S ) /\ z = [ ( p .+ q ) ] T ) ) = [ ( P .+ Q ) ] T ) ) | 
						
							| 69 | 57 68 | mpbid |  |-  ( ( ph /\ P e. A /\ Q e. B ) -> ( iota z E. p e. A E. q e. B ( ( [ P ] R = [ p ] R /\ [ Q ] S = [ q ] S ) /\ z = [ ( p .+ q ) ] T ) ) = [ ( P .+ Q ) ] T ) | 
						
							| 70 | 35 69 | eqtrd |  |-  ( ( ph /\ P e. A /\ Q e. B ) -> ( [ P ] R .+^ [ Q ] S ) = [ ( P .+ Q ) ] T ) |