| Step | Hyp | Ref | Expression | 
						
							| 1 |  | efgval.w |  |-  W = ( _I ` Word ( I X. 2o ) ) | 
						
							| 2 |  | efgval.r |  |-  .~ = ( ~FG ` I ) | 
						
							| 3 |  | efgval2.m |  |-  M = ( y e. I , z e. 2o |-> <. y , ( 1o \ z ) >. ) | 
						
							| 4 |  | efgval2.t |  |-  T = ( v e. W |-> ( n e. ( 0 ... ( # ` v ) ) , w e. ( I X. 2o ) |-> ( v splice <. n , n , <" w ( M ` w ) "> >. ) ) ) | 
						
							| 5 |  | efgred.d |  |-  D = ( W \ U_ x e. W ran ( T ` x ) ) | 
						
							| 6 |  | efgred.s |  |-  S = ( m e. { t e. ( Word W \ { (/) } ) | ( ( t ` 0 ) e. D /\ A. k e. ( 1 ..^ ( # ` t ) ) ( t ` k ) e. ran ( T ` ( t ` ( k - 1 ) ) ) ) } |-> ( m ` ( ( # ` m ) - 1 ) ) ) | 
						
							| 7 |  | efgredlem.1 |  |-  ( ph -> A. a e. dom S A. b e. dom S ( ( # ` ( S ` a ) ) < ( # ` ( S ` A ) ) -> ( ( S ` a ) = ( S ` b ) -> ( a ` 0 ) = ( b ` 0 ) ) ) ) | 
						
							| 8 |  | efgredlem.2 |  |-  ( ph -> A e. dom S ) | 
						
							| 9 |  | efgredlem.3 |  |-  ( ph -> B e. dom S ) | 
						
							| 10 |  | efgredlem.4 |  |-  ( ph -> ( S ` A ) = ( S ` B ) ) | 
						
							| 11 |  | efgredlem.5 |  |-  ( ph -> -. ( A ` 0 ) = ( B ` 0 ) ) | 
						
							| 12 |  | efgredlemb.k |  |-  K = ( ( ( # ` A ) - 1 ) - 1 ) | 
						
							| 13 |  | efgredlemb.l |  |-  L = ( ( ( # ` B ) - 1 ) - 1 ) | 
						
							| 14 |  | efgredlemb.p |  |-  ( ph -> P e. ( 0 ... ( # ` ( A ` K ) ) ) ) | 
						
							| 15 |  | efgredlemb.q |  |-  ( ph -> Q e. ( 0 ... ( # ` ( B ` L ) ) ) ) | 
						
							| 16 |  | efgredlemb.u |  |-  ( ph -> U e. ( I X. 2o ) ) | 
						
							| 17 |  | efgredlemb.v |  |-  ( ph -> V e. ( I X. 2o ) ) | 
						
							| 18 |  | efgredlemb.6 |  |-  ( ph -> ( S ` A ) = ( P ( T ` ( A ` K ) ) U ) ) | 
						
							| 19 |  | efgredlemb.7 |  |-  ( ph -> ( S ` B ) = ( Q ( T ` ( B ` L ) ) V ) ) | 
						
							| 20 |  | fviss |  |-  ( _I ` Word ( I X. 2o ) ) C_ Word ( I X. 2o ) | 
						
							| 21 | 1 20 | eqsstri |  |-  W C_ Word ( I X. 2o ) | 
						
							| 22 | 1 2 3 4 5 6 7 8 9 10 11 12 13 | efgredlemf |  |-  ( ph -> ( ( A ` K ) e. W /\ ( B ` L ) e. W ) ) | 
						
							| 23 | 22 | simpld |  |-  ( ph -> ( A ` K ) e. W ) | 
						
							| 24 | 21 23 | sselid |  |-  ( ph -> ( A ` K ) e. Word ( I X. 2o ) ) | 
						
							| 25 |  | lencl |  |-  ( ( A ` K ) e. Word ( I X. 2o ) -> ( # ` ( A ` K ) ) e. NN0 ) | 
						
							| 26 | 24 25 | syl |  |-  ( ph -> ( # ` ( A ` K ) ) e. NN0 ) | 
						
							| 27 | 26 | nn0cnd |  |-  ( ph -> ( # ` ( A ` K ) ) e. CC ) | 
						
							| 28 | 22 | simprd |  |-  ( ph -> ( B ` L ) e. W ) | 
						
							| 29 | 21 28 | sselid |  |-  ( ph -> ( B ` L ) e. Word ( I X. 2o ) ) | 
						
							| 30 |  | lencl |  |-  ( ( B ` L ) e. Word ( I X. 2o ) -> ( # ` ( B ` L ) ) e. NN0 ) | 
						
							| 31 | 29 30 | syl |  |-  ( ph -> ( # ` ( B ` L ) ) e. NN0 ) | 
						
							| 32 | 31 | nn0cnd |  |-  ( ph -> ( # ` ( B ` L ) ) e. CC ) | 
						
							| 33 |  | 2cnd |  |-  ( ph -> 2 e. CC ) | 
						
							| 34 | 1 2 3 4 5 6 7 8 9 10 11 | efgredlema |  |-  ( ph -> ( ( ( # ` A ) - 1 ) e. NN /\ ( ( # ` B ) - 1 ) e. NN ) ) | 
						
							| 35 | 34 | simpld |  |-  ( ph -> ( ( # ` A ) - 1 ) e. NN ) | 
						
							| 36 | 1 2 3 4 5 6 | efgsdmi |  |-  ( ( A e. dom S /\ ( ( # ` A ) - 1 ) e. NN ) -> ( S ` A ) e. ran ( T ` ( A ` ( ( ( # ` A ) - 1 ) - 1 ) ) ) ) | 
						
							| 37 | 8 35 36 | syl2anc |  |-  ( ph -> ( S ` A ) e. ran ( T ` ( A ` ( ( ( # ` A ) - 1 ) - 1 ) ) ) ) | 
						
							| 38 | 12 | fveq2i |  |-  ( A ` K ) = ( A ` ( ( ( # ` A ) - 1 ) - 1 ) ) | 
						
							| 39 | 38 | fveq2i |  |-  ( T ` ( A ` K ) ) = ( T ` ( A ` ( ( ( # ` A ) - 1 ) - 1 ) ) ) | 
						
							| 40 | 39 | rneqi |  |-  ran ( T ` ( A ` K ) ) = ran ( T ` ( A ` ( ( ( # ` A ) - 1 ) - 1 ) ) ) | 
						
							| 41 | 37 40 | eleqtrrdi |  |-  ( ph -> ( S ` A ) e. ran ( T ` ( A ` K ) ) ) | 
						
							| 42 | 1 2 3 4 | efgtlen |  |-  ( ( ( A ` K ) e. W /\ ( S ` A ) e. ran ( T ` ( A ` K ) ) ) -> ( # ` ( S ` A ) ) = ( ( # ` ( A ` K ) ) + 2 ) ) | 
						
							| 43 | 23 41 42 | syl2anc |  |-  ( ph -> ( # ` ( S ` A ) ) = ( ( # ` ( A ` K ) ) + 2 ) ) | 
						
							| 44 | 34 | simprd |  |-  ( ph -> ( ( # ` B ) - 1 ) e. NN ) | 
						
							| 45 | 1 2 3 4 5 6 | efgsdmi |  |-  ( ( B e. dom S /\ ( ( # ` B ) - 1 ) e. NN ) -> ( S ` B ) e. ran ( T ` ( B ` ( ( ( # ` B ) - 1 ) - 1 ) ) ) ) | 
						
							| 46 | 9 44 45 | syl2anc |  |-  ( ph -> ( S ` B ) e. ran ( T ` ( B ` ( ( ( # ` B ) - 1 ) - 1 ) ) ) ) | 
						
							| 47 | 10 46 | eqeltrd |  |-  ( ph -> ( S ` A ) e. ran ( T ` ( B ` ( ( ( # ` B ) - 1 ) - 1 ) ) ) ) | 
						
							| 48 | 13 | fveq2i |  |-  ( B ` L ) = ( B ` ( ( ( # ` B ) - 1 ) - 1 ) ) | 
						
							| 49 | 48 | fveq2i |  |-  ( T ` ( B ` L ) ) = ( T ` ( B ` ( ( ( # ` B ) - 1 ) - 1 ) ) ) | 
						
							| 50 | 49 | rneqi |  |-  ran ( T ` ( B ` L ) ) = ran ( T ` ( B ` ( ( ( # ` B ) - 1 ) - 1 ) ) ) | 
						
							| 51 | 47 50 | eleqtrrdi |  |-  ( ph -> ( S ` A ) e. ran ( T ` ( B ` L ) ) ) | 
						
							| 52 | 1 2 3 4 | efgtlen |  |-  ( ( ( B ` L ) e. W /\ ( S ` A ) e. ran ( T ` ( B ` L ) ) ) -> ( # ` ( S ` A ) ) = ( ( # ` ( B ` L ) ) + 2 ) ) | 
						
							| 53 | 28 51 52 | syl2anc |  |-  ( ph -> ( # ` ( S ` A ) ) = ( ( # ` ( B ` L ) ) + 2 ) ) | 
						
							| 54 | 43 53 | eqtr3d |  |-  ( ph -> ( ( # ` ( A ` K ) ) + 2 ) = ( ( # ` ( B ` L ) ) + 2 ) ) | 
						
							| 55 | 27 32 33 54 | addcan2ad |  |-  ( ph -> ( # ` ( A ` K ) ) = ( # ` ( B ` L ) ) ) |