| Step | Hyp | Ref | Expression | 
						
							| 1 |  | mapdh.q |  |-  Q = ( 0g ` C ) | 
						
							| 2 |  | mapdh.i |  |-  I = ( x e. _V |-> if ( ( 2nd ` x ) = .0. , Q , ( iota_ h e. D ( ( M ` ( N ` { ( 2nd ` x ) } ) ) = ( J ` { h } ) /\ ( M ` ( N ` { ( ( 1st ` ( 1st ` x ) ) .- ( 2nd ` x ) ) } ) ) = ( J ` { ( ( 2nd ` ( 1st ` x ) ) R h ) } ) ) ) ) ) | 
						
							| 3 |  | mapdh.x |  |-  ( ph -> X e. A ) | 
						
							| 4 |  | mapdh.f |  |-  ( ph -> F e. B ) | 
						
							| 5 |  | mapdh.y |  |-  ( ph -> Y e. E ) | 
						
							| 6 |  | otex |  |-  <. X , F , Y >. e. _V | 
						
							| 7 |  | fveq2 |  |-  ( x = <. X , F , Y >. -> ( 2nd ` x ) = ( 2nd ` <. X , F , Y >. ) ) | 
						
							| 8 | 7 | eqeq1d |  |-  ( x = <. X , F , Y >. -> ( ( 2nd ` x ) = .0. <-> ( 2nd ` <. X , F , Y >. ) = .0. ) ) | 
						
							| 9 | 7 | sneqd |  |-  ( x = <. X , F , Y >. -> { ( 2nd ` x ) } = { ( 2nd ` <. X , F , Y >. ) } ) | 
						
							| 10 | 9 | fveq2d |  |-  ( x = <. X , F , Y >. -> ( N ` { ( 2nd ` x ) } ) = ( N ` { ( 2nd ` <. X , F , Y >. ) } ) ) | 
						
							| 11 | 10 | fveqeq2d |  |-  ( x = <. X , F , Y >. -> ( ( M ` ( N ` { ( 2nd ` x ) } ) ) = ( J ` { h } ) <-> ( M ` ( N ` { ( 2nd ` <. X , F , Y >. ) } ) ) = ( J ` { h } ) ) ) | 
						
							| 12 |  | fveq2 |  |-  ( x = <. X , F , Y >. -> ( 1st ` x ) = ( 1st ` <. X , F , Y >. ) ) | 
						
							| 13 | 12 | fveq2d |  |-  ( x = <. X , F , Y >. -> ( 1st ` ( 1st ` x ) ) = ( 1st ` ( 1st ` <. X , F , Y >. ) ) ) | 
						
							| 14 | 13 7 | oveq12d |  |-  ( x = <. X , F , Y >. -> ( ( 1st ` ( 1st ` x ) ) .- ( 2nd ` x ) ) = ( ( 1st ` ( 1st ` <. X , F , Y >. ) ) .- ( 2nd ` <. X , F , Y >. ) ) ) | 
						
							| 15 | 14 | sneqd |  |-  ( x = <. X , F , Y >. -> { ( ( 1st ` ( 1st ` x ) ) .- ( 2nd ` x ) ) } = { ( ( 1st ` ( 1st ` <. X , F , Y >. ) ) .- ( 2nd ` <. X , F , Y >. ) ) } ) | 
						
							| 16 | 15 | fveq2d |  |-  ( x = <. X , F , Y >. -> ( N ` { ( ( 1st ` ( 1st ` x ) ) .- ( 2nd ` x ) ) } ) = ( N ` { ( ( 1st ` ( 1st ` <. X , F , Y >. ) ) .- ( 2nd ` <. X , F , Y >. ) ) } ) ) | 
						
							| 17 | 16 | fveq2d |  |-  ( x = <. X , F , Y >. -> ( M ` ( N ` { ( ( 1st ` ( 1st ` x ) ) .- ( 2nd ` x ) ) } ) ) = ( M ` ( N ` { ( ( 1st ` ( 1st ` <. X , F , Y >. ) ) .- ( 2nd ` <. X , F , Y >. ) ) } ) ) ) | 
						
							| 18 | 12 | fveq2d |  |-  ( x = <. X , F , Y >. -> ( 2nd ` ( 1st ` x ) ) = ( 2nd ` ( 1st ` <. X , F , Y >. ) ) ) | 
						
							| 19 | 18 | oveq1d |  |-  ( x = <. X , F , Y >. -> ( ( 2nd ` ( 1st ` x ) ) R h ) = ( ( 2nd ` ( 1st ` <. X , F , Y >. ) ) R h ) ) | 
						
							| 20 | 19 | sneqd |  |-  ( x = <. X , F , Y >. -> { ( ( 2nd ` ( 1st ` x ) ) R h ) } = { ( ( 2nd ` ( 1st ` <. X , F , Y >. ) ) R h ) } ) | 
						
							| 21 | 20 | fveq2d |  |-  ( x = <. X , F , Y >. -> ( J ` { ( ( 2nd ` ( 1st ` x ) ) R h ) } ) = ( J ` { ( ( 2nd ` ( 1st ` <. X , F , Y >. ) ) R h ) } ) ) | 
						
							| 22 | 17 21 | eqeq12d |  |-  ( x = <. X , F , Y >. -> ( ( M ` ( N ` { ( ( 1st ` ( 1st ` x ) ) .- ( 2nd ` x ) ) } ) ) = ( J ` { ( ( 2nd ` ( 1st ` x ) ) R h ) } ) <-> ( M ` ( N ` { ( ( 1st ` ( 1st ` <. X , F , Y >. ) ) .- ( 2nd ` <. X , F , Y >. ) ) } ) ) = ( J ` { ( ( 2nd ` ( 1st ` <. X , F , Y >. ) ) R h ) } ) ) ) | 
						
							| 23 | 11 22 | anbi12d |  |-  ( x = <. X , F , Y >. -> ( ( ( M ` ( N ` { ( 2nd ` x ) } ) ) = ( J ` { h } ) /\ ( M ` ( N ` { ( ( 1st ` ( 1st ` x ) ) .- ( 2nd ` x ) ) } ) ) = ( J ` { ( ( 2nd ` ( 1st ` x ) ) R h ) } ) ) <-> ( ( M ` ( N ` { ( 2nd ` <. X , F , Y >. ) } ) ) = ( J ` { h } ) /\ ( M ` ( N ` { ( ( 1st ` ( 1st ` <. X , F , Y >. ) ) .- ( 2nd ` <. X , F , Y >. ) ) } ) ) = ( J ` { ( ( 2nd ` ( 1st ` <. X , F , Y >. ) ) R h ) } ) ) ) ) | 
						
							| 24 | 23 | riotabidv |  |-  ( x = <. X , F , Y >. -> ( iota_ h e. D ( ( M ` ( N ` { ( 2nd ` x ) } ) ) = ( J ` { h } ) /\ ( M ` ( N ` { ( ( 1st ` ( 1st ` x ) ) .- ( 2nd ` x ) ) } ) ) = ( J ` { ( ( 2nd ` ( 1st ` x ) ) R h ) } ) ) ) = ( iota_ h e. D ( ( M ` ( N ` { ( 2nd ` <. X , F , Y >. ) } ) ) = ( J ` { h } ) /\ ( M ` ( N ` { ( ( 1st ` ( 1st ` <. X , F , Y >. ) ) .- ( 2nd ` <. X , F , Y >. ) ) } ) ) = ( J ` { ( ( 2nd ` ( 1st ` <. X , F , Y >. ) ) R h ) } ) ) ) ) | 
						
							| 25 | 8 24 | ifbieq2d |  |-  ( x = <. X , F , Y >. -> if ( ( 2nd ` x ) = .0. , Q , ( iota_ h e. D ( ( M ` ( N ` { ( 2nd ` x ) } ) ) = ( J ` { h } ) /\ ( M ` ( N ` { ( ( 1st ` ( 1st ` x ) ) .- ( 2nd ` x ) ) } ) ) = ( J ` { ( ( 2nd ` ( 1st ` x ) ) R h ) } ) ) ) ) = if ( ( 2nd ` <. X , F , Y >. ) = .0. , Q , ( iota_ h e. D ( ( M ` ( N ` { ( 2nd ` <. X , F , Y >. ) } ) ) = ( J ` { h } ) /\ ( M ` ( N ` { ( ( 1st ` ( 1st ` <. X , F , Y >. ) ) .- ( 2nd ` <. X , F , Y >. ) ) } ) ) = ( J ` { ( ( 2nd ` ( 1st ` <. X , F , Y >. ) ) R h ) } ) ) ) ) ) | 
						
							| 26 | 1 | fvexi |  |-  Q e. _V | 
						
							| 27 |  | riotaex |  |-  ( iota_ h e. D ( ( M ` ( N ` { ( 2nd ` <. X , F , Y >. ) } ) ) = ( J ` { h } ) /\ ( M ` ( N ` { ( ( 1st ` ( 1st ` <. X , F , Y >. ) ) .- ( 2nd ` <. X , F , Y >. ) ) } ) ) = ( J ` { ( ( 2nd ` ( 1st ` <. X , F , Y >. ) ) R h ) } ) ) ) e. _V | 
						
							| 28 | 26 27 | ifex |  |-  if ( ( 2nd ` <. X , F , Y >. ) = .0. , Q , ( iota_ h e. D ( ( M ` ( N ` { ( 2nd ` <. X , F , Y >. ) } ) ) = ( J ` { h } ) /\ ( M ` ( N ` { ( ( 1st ` ( 1st ` <. X , F , Y >. ) ) .- ( 2nd ` <. X , F , Y >. ) ) } ) ) = ( J ` { ( ( 2nd ` ( 1st ` <. X , F , Y >. ) ) R h ) } ) ) ) ) e. _V | 
						
							| 29 | 25 2 28 | fvmpt |  |-  ( <. X , F , Y >. e. _V -> ( I ` <. X , F , Y >. ) = if ( ( 2nd ` <. X , F , Y >. ) = .0. , Q , ( iota_ h e. D ( ( M ` ( N ` { ( 2nd ` <. X , F , Y >. ) } ) ) = ( J ` { h } ) /\ ( M ` ( N ` { ( ( 1st ` ( 1st ` <. X , F , Y >. ) ) .- ( 2nd ` <. X , F , Y >. ) ) } ) ) = ( J ` { ( ( 2nd ` ( 1st ` <. X , F , Y >. ) ) R h ) } ) ) ) ) ) | 
						
							| 30 | 6 29 | mp1i |  |-  ( ph -> ( I ` <. X , F , Y >. ) = if ( ( 2nd ` <. X , F , Y >. ) = .0. , Q , ( iota_ h e. D ( ( M ` ( N ` { ( 2nd ` <. X , F , Y >. ) } ) ) = ( J ` { h } ) /\ ( M ` ( N ` { ( ( 1st ` ( 1st ` <. X , F , Y >. ) ) .- ( 2nd ` <. X , F , Y >. ) ) } ) ) = ( J ` { ( ( 2nd ` ( 1st ` <. X , F , Y >. ) ) R h ) } ) ) ) ) ) | 
						
							| 31 |  | ot3rdg |  |-  ( Y e. E -> ( 2nd ` <. X , F , Y >. ) = Y ) | 
						
							| 32 | 5 31 | syl |  |-  ( ph -> ( 2nd ` <. X , F , Y >. ) = Y ) | 
						
							| 33 | 32 | eqeq1d |  |-  ( ph -> ( ( 2nd ` <. X , F , Y >. ) = .0. <-> Y = .0. ) ) | 
						
							| 34 | 32 | sneqd |  |-  ( ph -> { ( 2nd ` <. X , F , Y >. ) } = { Y } ) | 
						
							| 35 | 34 | fveq2d |  |-  ( ph -> ( N ` { ( 2nd ` <. X , F , Y >. ) } ) = ( N ` { Y } ) ) | 
						
							| 36 | 35 | fveqeq2d |  |-  ( ph -> ( ( M ` ( N ` { ( 2nd ` <. X , F , Y >. ) } ) ) = ( J ` { h } ) <-> ( M ` ( N ` { Y } ) ) = ( J ` { h } ) ) ) | 
						
							| 37 |  | ot1stg |  |-  ( ( X e. A /\ F e. B /\ Y e. E ) -> ( 1st ` ( 1st ` <. X , F , Y >. ) ) = X ) | 
						
							| 38 | 3 4 5 37 | syl3anc |  |-  ( ph -> ( 1st ` ( 1st ` <. X , F , Y >. ) ) = X ) | 
						
							| 39 | 38 32 | oveq12d |  |-  ( ph -> ( ( 1st ` ( 1st ` <. X , F , Y >. ) ) .- ( 2nd ` <. X , F , Y >. ) ) = ( X .- Y ) ) | 
						
							| 40 | 39 | sneqd |  |-  ( ph -> { ( ( 1st ` ( 1st ` <. X , F , Y >. ) ) .- ( 2nd ` <. X , F , Y >. ) ) } = { ( X .- Y ) } ) | 
						
							| 41 | 40 | fveq2d |  |-  ( ph -> ( N ` { ( ( 1st ` ( 1st ` <. X , F , Y >. ) ) .- ( 2nd ` <. X , F , Y >. ) ) } ) = ( N ` { ( X .- Y ) } ) ) | 
						
							| 42 | 41 | fveq2d |  |-  ( ph -> ( M ` ( N ` { ( ( 1st ` ( 1st ` <. X , F , Y >. ) ) .- ( 2nd ` <. X , F , Y >. ) ) } ) ) = ( M ` ( N ` { ( X .- Y ) } ) ) ) | 
						
							| 43 |  | ot2ndg |  |-  ( ( X e. A /\ F e. B /\ Y e. E ) -> ( 2nd ` ( 1st ` <. X , F , Y >. ) ) = F ) | 
						
							| 44 | 3 4 5 43 | syl3anc |  |-  ( ph -> ( 2nd ` ( 1st ` <. X , F , Y >. ) ) = F ) | 
						
							| 45 | 44 | oveq1d |  |-  ( ph -> ( ( 2nd ` ( 1st ` <. X , F , Y >. ) ) R h ) = ( F R h ) ) | 
						
							| 46 | 45 | sneqd |  |-  ( ph -> { ( ( 2nd ` ( 1st ` <. X , F , Y >. ) ) R h ) } = { ( F R h ) } ) | 
						
							| 47 | 46 | fveq2d |  |-  ( ph -> ( J ` { ( ( 2nd ` ( 1st ` <. X , F , Y >. ) ) R h ) } ) = ( J ` { ( F R h ) } ) ) | 
						
							| 48 | 42 47 | eqeq12d |  |-  ( ph -> ( ( M ` ( N ` { ( ( 1st ` ( 1st ` <. X , F , Y >. ) ) .- ( 2nd ` <. X , F , Y >. ) ) } ) ) = ( J ` { ( ( 2nd ` ( 1st ` <. X , F , Y >. ) ) R h ) } ) <-> ( M ` ( N ` { ( X .- Y ) } ) ) = ( J ` { ( F R h ) } ) ) ) | 
						
							| 49 | 36 48 | anbi12d |  |-  ( ph -> ( ( ( M ` ( N ` { ( 2nd ` <. X , F , Y >. ) } ) ) = ( J ` { h } ) /\ ( M ` ( N ` { ( ( 1st ` ( 1st ` <. X , F , Y >. ) ) .- ( 2nd ` <. X , F , Y >. ) ) } ) ) = ( J ` { ( ( 2nd ` ( 1st ` <. X , F , Y >. ) ) R h ) } ) ) <-> ( ( M ` ( N ` { Y } ) ) = ( J ` { h } ) /\ ( M ` ( N ` { ( X .- Y ) } ) ) = ( J ` { ( F R h ) } ) ) ) ) | 
						
							| 50 | 49 | riotabidv |  |-  ( ph -> ( iota_ h e. D ( ( M ` ( N ` { ( 2nd ` <. X , F , Y >. ) } ) ) = ( J ` { h } ) /\ ( M ` ( N ` { ( ( 1st ` ( 1st ` <. X , F , Y >. ) ) .- ( 2nd ` <. X , F , Y >. ) ) } ) ) = ( J ` { ( ( 2nd ` ( 1st ` <. X , F , Y >. ) ) R h ) } ) ) ) = ( iota_ h e. D ( ( M ` ( N ` { Y } ) ) = ( J ` { h } ) /\ ( M ` ( N ` { ( X .- Y ) } ) ) = ( J ` { ( F R h ) } ) ) ) ) | 
						
							| 51 | 33 50 | ifbieq2d |  |-  ( ph -> if ( ( 2nd ` <. X , F , Y >. ) = .0. , Q , ( iota_ h e. D ( ( M ` ( N ` { ( 2nd ` <. X , F , Y >. ) } ) ) = ( J ` { h } ) /\ ( M ` ( N ` { ( ( 1st ` ( 1st ` <. X , F , Y >. ) ) .- ( 2nd ` <. X , F , Y >. ) ) } ) ) = ( J ` { ( ( 2nd ` ( 1st ` <. X , F , Y >. ) ) R h ) } ) ) ) ) = if ( Y = .0. , Q , ( iota_ h e. D ( ( M ` ( N ` { Y } ) ) = ( J ` { h } ) /\ ( M ` ( N ` { ( X .- Y ) } ) ) = ( J ` { ( F R h ) } ) ) ) ) ) | 
						
							| 52 | 30 51 | eqtrd |  |-  ( ph -> ( I ` <. X , F , Y >. ) = if ( Y = .0. , Q , ( iota_ h e. D ( ( M ` ( N ` { Y } ) ) = ( J ` { h } ) /\ ( M ` ( N ` { ( X .- Y ) } ) ) = ( J ` { ( F R h ) } ) ) ) ) ) |