| Step | Hyp | Ref | Expression | 
						
							| 1 |  | rexfrabdioph.1 |  |-  M = ( N + 1 ) | 
						
							| 2 |  | rexfrabdioph.2 |  |-  L = ( M + 1 ) | 
						
							| 3 |  | rexfrabdioph.3 |  |-  K = ( L + 1 ) | 
						
							| 4 |  | sbc2rex |  |-  ( [. ( a ` M ) / v ]. E. w e. NN0 E. x e. NN0 ph <-> E. w e. NN0 E. x e. NN0 [. ( a ` M ) / v ]. ph ) | 
						
							| 5 | 4 | sbcbii |  |-  ( [. ( a |` ( 1 ... N ) ) / u ]. [. ( a ` M ) / v ]. E. w e. NN0 E. x e. NN0 ph <-> [. ( a |` ( 1 ... N ) ) / u ]. E. w e. NN0 E. x e. NN0 [. ( a ` M ) / v ]. ph ) | 
						
							| 6 |  | sbc2rex |  |-  ( [. ( a |` ( 1 ... N ) ) / u ]. E. w e. NN0 E. x e. NN0 [. ( a ` M ) / v ]. ph <-> E. w e. NN0 E. x e. NN0 [. ( a |` ( 1 ... N ) ) / u ]. [. ( a ` M ) / v ]. ph ) | 
						
							| 7 | 5 6 | bitri |  |-  ( [. ( a |` ( 1 ... N ) ) / u ]. [. ( a ` M ) / v ]. E. w e. NN0 E. x e. NN0 ph <-> E. w e. NN0 E. x e. NN0 [. ( a |` ( 1 ... N ) ) / u ]. [. ( a ` M ) / v ]. ph ) | 
						
							| 8 | 7 | rabbii |  |-  { a e. ( NN0 ^m ( 1 ... M ) ) | [. ( a |` ( 1 ... N ) ) / u ]. [. ( a ` M ) / v ]. E. w e. NN0 E. x e. NN0 ph } = { a e. ( NN0 ^m ( 1 ... M ) ) | E. w e. NN0 E. x e. NN0 [. ( a |` ( 1 ... N ) ) / u ]. [. ( a ` M ) / v ]. ph } | 
						
							| 9 |  | nn0p1nn |  |-  ( N e. NN0 -> ( N + 1 ) e. NN ) | 
						
							| 10 | 1 9 | eqeltrid |  |-  ( N e. NN0 -> M e. NN ) | 
						
							| 11 | 10 | nnnn0d |  |-  ( N e. NN0 -> M e. NN0 ) | 
						
							| 12 | 11 | adantr |  |-  ( ( N e. NN0 /\ { t e. ( NN0 ^m ( 1 ... K ) ) | [. ( t |` ( 1 ... N ) ) / u ]. [. ( t ` M ) / v ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. ph } e. ( Dioph ` K ) ) -> M e. NN0 ) | 
						
							| 13 |  | sbcrot3 |  |-  ( [. ( a ` M ) / v ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. ph <-> [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. [. ( a ` M ) / v ]. ph ) | 
						
							| 14 | 13 | sbcbii |  |-  ( [. ( a |` ( 1 ... N ) ) / u ]. [. ( a ` M ) / v ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. ph <-> [. ( a |` ( 1 ... N ) ) / u ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. [. ( a ` M ) / v ]. ph ) | 
						
							| 15 |  | sbcrot3 |  |-  ( [. ( a |` ( 1 ... N ) ) / u ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. [. ( a ` M ) / v ]. ph <-> [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. [. ( a |` ( 1 ... N ) ) / u ]. [. ( a ` M ) / v ]. ph ) | 
						
							| 16 | 14 15 | bitri |  |-  ( [. ( a |` ( 1 ... N ) ) / u ]. [. ( a ` M ) / v ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. ph <-> [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. [. ( a |` ( 1 ... N ) ) / u ]. [. ( a ` M ) / v ]. ph ) | 
						
							| 17 | 16 | sbcbii |  |-  ( [. ( t |` ( 1 ... M ) ) / a ]. [. ( a |` ( 1 ... N ) ) / u ]. [. ( a ` M ) / v ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. ph <-> [. ( t |` ( 1 ... M ) ) / a ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. [. ( a |` ( 1 ... N ) ) / u ]. [. ( a ` M ) / v ]. ph ) | 
						
							| 18 |  | reseq1 |  |-  ( a = ( t |` ( 1 ... M ) ) -> ( a |` ( 1 ... N ) ) = ( ( t |` ( 1 ... M ) ) |` ( 1 ... N ) ) ) | 
						
							| 19 | 18 | sbccomieg |  |-  ( [. ( t |` ( 1 ... M ) ) / a ]. [. ( a |` ( 1 ... N ) ) / u ]. [. ( a ` M ) / v ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. ph <-> [. ( ( t |` ( 1 ... M ) ) |` ( 1 ... N ) ) / u ]. [. ( t |` ( 1 ... M ) ) / a ]. [. ( a ` M ) / v ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. ph ) | 
						
							| 20 |  | fzssp1 |  |-  ( 1 ... N ) C_ ( 1 ... ( N + 1 ) ) | 
						
							| 21 | 1 | oveq2i |  |-  ( 1 ... M ) = ( 1 ... ( N + 1 ) ) | 
						
							| 22 | 20 21 | sseqtrri |  |-  ( 1 ... N ) C_ ( 1 ... M ) | 
						
							| 23 |  | resabs1 |  |-  ( ( 1 ... N ) C_ ( 1 ... M ) -> ( ( t |` ( 1 ... M ) ) |` ( 1 ... N ) ) = ( t |` ( 1 ... N ) ) ) | 
						
							| 24 |  | dfsbcq |  |-  ( ( ( t |` ( 1 ... M ) ) |` ( 1 ... N ) ) = ( t |` ( 1 ... N ) ) -> ( [. ( ( t |` ( 1 ... M ) ) |` ( 1 ... N ) ) / u ]. [. ( t |` ( 1 ... M ) ) / a ]. [. ( a ` M ) / v ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. ph <-> [. ( t |` ( 1 ... N ) ) / u ]. [. ( t |` ( 1 ... M ) ) / a ]. [. ( a ` M ) / v ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. ph ) ) | 
						
							| 25 | 22 23 24 | mp2b |  |-  ( [. ( ( t |` ( 1 ... M ) ) |` ( 1 ... N ) ) / u ]. [. ( t |` ( 1 ... M ) ) / a ]. [. ( a ` M ) / v ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. ph <-> [. ( t |` ( 1 ... N ) ) / u ]. [. ( t |` ( 1 ... M ) ) / a ]. [. ( a ` M ) / v ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. ph ) | 
						
							| 26 |  | vex |  |-  t e. _V | 
						
							| 27 | 26 | resex |  |-  ( t |` ( 1 ... M ) ) e. _V | 
						
							| 28 |  | fveq1 |  |-  ( a = ( t |` ( 1 ... M ) ) -> ( a ` M ) = ( ( t |` ( 1 ... M ) ) ` M ) ) | 
						
							| 29 | 28 | sbcco3gw |  |-  ( ( t |` ( 1 ... M ) ) e. _V -> ( [. ( t |` ( 1 ... M ) ) / a ]. [. ( a ` M ) / v ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. ph <-> [. ( ( t |` ( 1 ... M ) ) ` M ) / v ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. ph ) ) | 
						
							| 30 | 27 29 | ax-mp |  |-  ( [. ( t |` ( 1 ... M ) ) / a ]. [. ( a ` M ) / v ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. ph <-> [. ( ( t |` ( 1 ... M ) ) ` M ) / v ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. ph ) | 
						
							| 31 |  | elfz1end |  |-  ( M e. NN <-> M e. ( 1 ... M ) ) | 
						
							| 32 | 10 31 | sylib |  |-  ( N e. NN0 -> M e. ( 1 ... M ) ) | 
						
							| 33 |  | fvres |  |-  ( M e. ( 1 ... M ) -> ( ( t |` ( 1 ... M ) ) ` M ) = ( t ` M ) ) | 
						
							| 34 |  | dfsbcq |  |-  ( ( ( t |` ( 1 ... M ) ) ` M ) = ( t ` M ) -> ( [. ( ( t |` ( 1 ... M ) ) ` M ) / v ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. ph <-> [. ( t ` M ) / v ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. ph ) ) | 
						
							| 35 | 32 33 34 | 3syl |  |-  ( N e. NN0 -> ( [. ( ( t |` ( 1 ... M ) ) ` M ) / v ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. ph <-> [. ( t ` M ) / v ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. ph ) ) | 
						
							| 36 | 30 35 | bitrid |  |-  ( N e. NN0 -> ( [. ( t |` ( 1 ... M ) ) / a ]. [. ( a ` M ) / v ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. ph <-> [. ( t ` M ) / v ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. ph ) ) | 
						
							| 37 | 36 | sbcbidv |  |-  ( N e. NN0 -> ( [. ( t |` ( 1 ... N ) ) / u ]. [. ( t |` ( 1 ... M ) ) / a ]. [. ( a ` M ) / v ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. ph <-> [. ( t |` ( 1 ... N ) ) / u ]. [. ( t ` M ) / v ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. ph ) ) | 
						
							| 38 | 25 37 | bitrid |  |-  ( N e. NN0 -> ( [. ( ( t |` ( 1 ... M ) ) |` ( 1 ... N ) ) / u ]. [. ( t |` ( 1 ... M ) ) / a ]. [. ( a ` M ) / v ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. ph <-> [. ( t |` ( 1 ... N ) ) / u ]. [. ( t ` M ) / v ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. ph ) ) | 
						
							| 39 | 19 38 | bitrid |  |-  ( N e. NN0 -> ( [. ( t |` ( 1 ... M ) ) / a ]. [. ( a |` ( 1 ... N ) ) / u ]. [. ( a ` M ) / v ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. ph <-> [. ( t |` ( 1 ... N ) ) / u ]. [. ( t ` M ) / v ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. ph ) ) | 
						
							| 40 | 17 39 | bitr3id |  |-  ( N e. NN0 -> ( [. ( t |` ( 1 ... M ) ) / a ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. [. ( a |` ( 1 ... N ) ) / u ]. [. ( a ` M ) / v ]. ph <-> [. ( t |` ( 1 ... N ) ) / u ]. [. ( t ` M ) / v ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. ph ) ) | 
						
							| 41 | 40 | rabbidv |  |-  ( N e. NN0 -> { t e. ( NN0 ^m ( 1 ... K ) ) | [. ( t |` ( 1 ... M ) ) / a ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. [. ( a |` ( 1 ... N ) ) / u ]. [. ( a ` M ) / v ]. ph } = { t e. ( NN0 ^m ( 1 ... K ) ) | [. ( t |` ( 1 ... N ) ) / u ]. [. ( t ` M ) / v ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. ph } ) | 
						
							| 42 | 41 | eleq1d |  |-  ( N e. NN0 -> ( { t e. ( NN0 ^m ( 1 ... K ) ) | [. ( t |` ( 1 ... M ) ) / a ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. [. ( a |` ( 1 ... N ) ) / u ]. [. ( a ` M ) / v ]. ph } e. ( Dioph ` K ) <-> { t e. ( NN0 ^m ( 1 ... K ) ) | [. ( t |` ( 1 ... N ) ) / u ]. [. ( t ` M ) / v ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. ph } e. ( Dioph ` K ) ) ) | 
						
							| 43 | 42 | biimpar |  |-  ( ( N e. NN0 /\ { t e. ( NN0 ^m ( 1 ... K ) ) | [. ( t |` ( 1 ... N ) ) / u ]. [. ( t ` M ) / v ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. ph } e. ( Dioph ` K ) ) -> { t e. ( NN0 ^m ( 1 ... K ) ) | [. ( t |` ( 1 ... M ) ) / a ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. [. ( a |` ( 1 ... N ) ) / u ]. [. ( a ` M ) / v ]. ph } e. ( Dioph ` K ) ) | 
						
							| 44 | 2 3 | 2rexfrabdioph |  |-  ( ( M e. NN0 /\ { t e. ( NN0 ^m ( 1 ... K ) ) | [. ( t |` ( 1 ... M ) ) / a ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. [. ( a |` ( 1 ... N ) ) / u ]. [. ( a ` M ) / v ]. ph } e. ( Dioph ` K ) ) -> { a e. ( NN0 ^m ( 1 ... M ) ) | E. w e. NN0 E. x e. NN0 [. ( a |` ( 1 ... N ) ) / u ]. [. ( a ` M ) / v ]. ph } e. ( Dioph ` M ) ) | 
						
							| 45 | 12 43 44 | syl2anc |  |-  ( ( N e. NN0 /\ { t e. ( NN0 ^m ( 1 ... K ) ) | [. ( t |` ( 1 ... N ) ) / u ]. [. ( t ` M ) / v ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. ph } e. ( Dioph ` K ) ) -> { a e. ( NN0 ^m ( 1 ... M ) ) | E. w e. NN0 E. x e. NN0 [. ( a |` ( 1 ... N ) ) / u ]. [. ( a ` M ) / v ]. ph } e. ( Dioph ` M ) ) | 
						
							| 46 | 8 45 | eqeltrid |  |-  ( ( N e. NN0 /\ { t e. ( NN0 ^m ( 1 ... K ) ) | [. ( t |` ( 1 ... N ) ) / u ]. [. ( t ` M ) / v ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. ph } e. ( Dioph ` K ) ) -> { a e. ( NN0 ^m ( 1 ... M ) ) | [. ( a |` ( 1 ... N ) ) / u ]. [. ( a ` M ) / v ]. E. w e. NN0 E. x e. NN0 ph } e. ( Dioph ` M ) ) | 
						
							| 47 | 1 | rexfrabdioph |  |-  ( ( N e. NN0 /\ { a e. ( NN0 ^m ( 1 ... M ) ) | [. ( a |` ( 1 ... N ) ) / u ]. [. ( a ` M ) / v ]. E. w e. NN0 E. x e. NN0 ph } e. ( Dioph ` M ) ) -> { u e. ( NN0 ^m ( 1 ... N ) ) | E. v e. NN0 E. w e. NN0 E. x e. NN0 ph } e. ( Dioph ` N ) ) | 
						
							| 48 | 46 47 | syldan |  |-  ( ( N e. NN0 /\ { t e. ( NN0 ^m ( 1 ... K ) ) | [. ( t |` ( 1 ... N ) ) / u ]. [. ( t ` M ) / v ]. [. ( t ` L ) / w ]. [. ( t ` K ) / x ]. ph } e. ( Dioph ` K ) ) -> { u e. ( NN0 ^m ( 1 ... N ) ) | E. v e. NN0 E. w e. NN0 E. x e. NN0 ph } e. ( Dioph ` N ) ) |