let v be LTL-formula; :: thesis: for N being strict LTLnode of v ex n being Nat ex L being FinSequence ex M being strict LTLnode of v st
( 1 <= n & len L = n & L . 1 = N & L . n = M & the LTLnew of M = {} v & L is_Finseq_for v )

let N be strict LTLnode of v; :: thesis: ex n being Nat ex L being FinSequence ex M being strict LTLnode of v st
( 1 <= n & len L = n & L . 1 = N & L . n = M & the LTLnew of M = {} v & L is_Finseq_for v )

defpred S1[ Nat] means for N being strict LTLnode of v st len N <= $1 holds
ex n being Nat ex L being FinSequence ex M being strict LTLnode of v st
( 1 <= n & len L = n & L . 1 = N & L . n = M & the LTLnew of M = {} v & L is_Finseq_for v );
A1: S1[ 0 ]
proof
let N be strict LTLnode of v; :: thesis: ( len N <= 0 implies ex n being Nat ex L being FinSequence ex M being strict LTLnode of v st
( 1 <= n & len L = n & L . 1 = N & L . n = M & the LTLnew of M = {} v & L is_Finseq_for v ) )

( len N <= 0 implies ex n being Nat ex L being FinSequence ex M being strict LTLnode of v st
( 1 <= n & len L = n & L . 1 = N & L . n = M & the LTLnew of M = {} v & L is_Finseq_for v ) )
proof
assume B1: len N <= 0 ; :: thesis: ex n being Nat ex L being FinSequence ex M being strict LTLnode of v st
( 1 <= n & len L = n & L . 1 = N & L . n = M & the LTLnew of M = {} v & L is_Finseq_for v )

set M = N;
set n = 1;
set L = <*N*>;
B3: for k being Nat st 1 <= k & k < len <*N*> holds
ex N1, N2 being strict LTLnode of v st
( <*N*> . k = N1 & <*N*> . (k + 1) = N2 & N2 is_succ_of N1 ) by FINSEQ_1:56;
take 1 ; :: thesis: ex L being FinSequence ex M being strict LTLnode of v st
( 1 <= 1 & len L = 1 & L . 1 = N & L . 1 = M & the LTLnew of M = {} v & L is_Finseq_for v )

take <*N*> ; :: thesis: ex M being strict LTLnode of v st
( 1 <= 1 & len <*N*> = 1 & <*N*> . 1 = N & <*N*> . 1 = M & the LTLnew of M = {} v & <*N*> is_Finseq_for v )

take N ; :: thesis: ( 1 <= 1 & len <*N*> = 1 & <*N*> . 1 = N & <*N*> . 1 = N & the LTLnew of N = {} v & <*N*> is_Finseq_for v )
thus ( 1 <= 1 & len <*N*> = 1 & <*N*> . 1 = N & <*N*> . 1 = N & the LTLnew of N = {} v & <*N*> is_Finseq_for v ) by B1, Thlen18, B3, DefFinseq, FINSEQ_1:57; :: thesis: verum
end;
hence ( len N <= 0 implies ex n being Nat ex L being FinSequence ex M being strict LTLnode of v st
( 1 <= n & len L = n & L . 1 = N & L . n = M & the LTLnew of M = {} v & L is_Finseq_for v ) ) ; :: thesis: verum
end;
A2: for l being Nat st S1[l] holds
S1[l + 1]
proof
let l be Nat; :: thesis: ( S1[l] implies S1[l + 1] )
assume B1: S1[l] ; :: thesis: S1[l + 1]
S1[l + 1]
proof
let N be strict LTLnode of v; :: thesis: ( len N <= l + 1 implies ex n being Nat ex L being FinSequence ex M being strict LTLnode of v st
( 1 <= n & len L = n & L . 1 = N & L . n = M & the LTLnew of M = {} v & L is_Finseq_for v ) )

( len N <= l + 1 implies ex n being Nat ex L being FinSequence ex M being strict LTLnode of v st
( 1 <= n & len L = n & L . 1 = N & L . n = M & the LTLnew of M = {} v & L is_Finseq_for v ) )
proof
assume C0: len N <= l + 1 ; :: thesis: ex n being Nat ex L being FinSequence ex M being strict LTLnode of v st
( 1 <= n & len L = n & L . 1 = N & L . n = M & the LTLnew of M = {} v & L is_Finseq_for v )

ex n being Nat ex L being FinSequence ex M being strict LTLnode of v st
( 1 <= n & len L = n & L . 1 = N & L . n = M & the LTLnew of M = {} v & L is_Finseq_for v )
proof
set NewN = the LTLnew of N;
now
per cases ( len N <= l or len N = l + 1 ) by C0, NAT_1:8;
suppose len N <= l ; :: thesis: ex n being Nat ex L being FinSequence ex M being strict LTLnode of v st
( 1 <= n & len L = n & L . 1 = N & L . n = M & the LTLnew of M = {} v & L is_Finseq_for v )

hence ex n being Nat ex L being FinSequence ex M being strict LTLnode of v st
( 1 <= n & len L = n & L . 1 = N & L . n = M & the LTLnew of M = {} v & L is_Finseq_for v ) by B1; :: thesis: verum
end;
suppose C2: len N = l + 1 ; :: thesis: ex n being Nat ex L being FinSequence ex M being strict LTLnode of v st
( 1 <= n & len L = n & L . 1 = N & L . n = M & the LTLnew of M = {} v & L is_Finseq_for v )

then the LTLnew of N <> {} v by Thlen19;
then consider x being set such that
D1: x in the LTLnew of N by XBOOLE_0:def 1;
x in Subformulae v by D1;
then reconsider x = x as LTL-formula by MODELC_2:1;
set M1 = SuccNode1 x,N;
SuccNode1 x,N is_succ1_of N by D1, Def208;
then D2: SuccNode1 x,N is_succ_of N by Def210;
then len (SuccNode1 x,N) <= (len N) - 1 by Thlen17;
then consider n being Nat, L being FinSequence, M being strict LTLnode of v such that
D3: ( 1 <= n & len L = n & L . 1 = SuccNode1 x,N & L . n = M & the LTLnew of M = {} v & L is_Finseq_for v ) by C2, B1;
set n1 = n + 1;
D301: 1 < n + 1 by D3, NAT_1:13;
set L1 = <*N*> ^ L;
D5: len (<*N*> ^ L) = (len <*N*>) + (len L) by FINSEQ_1:35
.= n + 1 by D3, FINSEQ_1:56 ;
D6: (<*N*> ^ L) . 1 = N by FINSEQ_1:58;
len <*N*> = 1 by FINSEQ_1:56;
then D7: (<*N*> ^ L) . (n + 1) = L . ((n + 1) - 1) by D301, D5, FINSEQ_1:37
.= M by D3 ;
<*N*> ^ L is_Finseq_for v
proof
let k be Nat; :: according to MODELC_3:def 19 :: thesis: ( 1 <= k & k < len (<*N*> ^ L) implies ex N, M being strict LTLnode of v st
( N = (<*N*> ^ L) . k & M = (<*N*> ^ L) . (k + 1) & M is_succ_of N ) )

assume that
E1: 1 <= k and
E2: k < len (<*N*> ^ L) ; :: thesis: ex N, M being strict LTLnode of v st
( N = (<*N*> ^ L) . k & M = (<*N*> ^ L) . (k + 1) & M is_succ_of N )

E3: k + 1 <= len (<*N*> ^ L) by E2, NAT_1:13;
ex N1, N2 being strict LTLnode of v st
( (<*N*> ^ L) . k = N1 & (<*N*> ^ L) . (k + 1) = N2 & N2 is_succ_of N1 )
proof
set N1 = (<*N*> ^ L) . k;
set N2 = (<*N*> ^ L) . (k + 1);
now
per cases ( k <= 1 or 1 < k ) ;
suppose k <= 1 ; :: thesis: ex N1, N2, N1, N2 being strict LTLnode of v st
( (<*N*> ^ L) . k = N1 & (<*N*> ^ L) . (k + 1) = N2 & N2 is_succ_of N1 )

then E101: k = 1 by E1, XXREAL_0:1;
reconsider N1 = (<*N*> ^ L) . k as strict LTLnode of v by E101, FINSEQ_1:58;
E104: len <*N*> = 1 by FINSEQ_1:56;
E105: (<*N*> ^ L) . (k + 1) = L . (2 - 1) by E104, E101, E3, FINSEQ_1:37
.= SuccNode1 x,N by D3 ;
then reconsider N2 = (<*N*> ^ L) . (k + 1) as strict LTLnode of v ;
take N1 = N1; :: thesis: ex N2, N1, N2 being strict LTLnode of v st
( (<*N*> ^ L) . k = N1 & (<*N*> ^ L) . (k + 1) = N2 & N2 is_succ_of N1 )

take N2 = N2; :: thesis: ex N1, N2 being strict LTLnode of v st
( (<*N*> ^ L) . k = N1 & (<*N*> ^ L) . (k + 1) = N2 & N2 is_succ_of N1 )

thus ex N1, N2 being strict LTLnode of v st
( (<*N*> ^ L) . k = N1 & (<*N*> ^ L) . (k + 1) = N2 & N2 is_succ_of N1 ) by E101, E105, D2, FINSEQ_1:58; :: thesis: verum
end;
suppose E200: 1 < k ; :: thesis: ex N1, N2, N1, N2 being strict LTLnode of v st
( (<*N*> ^ L) . k = N1 & (<*N*> ^ L) . (k + 1) = N2 & N2 is_succ_of N1 )

then E201: len <*N*> < k by FINSEQ_1:56;
k <= k + 1 by NAT_1:11;
then E202: len <*N*> < k + 1 by E201, XXREAL_0:2;
set km1 = k - 1;
reconsider km1 = k - 1 as Nat by E200, NAT_1:20;
1 < km1 + 1 by E200;
then E203: 1 <= km1 by NAT_1:13;
E204: km1 < (n + 1) - 1 by E2, D5, XREAL_1:16;
E205: (<*N*> ^ L) . k = L . (k - (len <*N*>)) by E2, E201, FINSEQ_1:37
.= L . km1 by FINSEQ_1:56 ;
E206: (<*N*> ^ L) . (k + 1) = L . ((k + 1) - (len <*N*>)) by E3, E202, FINSEQ_1:37
.= L . ((k + 1) - 1) by FINSEQ_1:56
.= L . (km1 + 1) ;
consider N10, N20 being strict LTLnode of v such that
E207: ( L . km1 = N10 & L . (km1 + 1) = N20 & N20 is_succ_of N10 ) by E203, E204, D3, DefFinseq;
reconsider N1 = (<*N*> ^ L) . k as strict LTLnode of v by E205, E207;
reconsider N2 = (<*N*> ^ L) . (k + 1) as strict LTLnode of v by E206, E207;
take N1 = N1; :: thesis: ex N2, N1, N2 being strict LTLnode of v st
( (<*N*> ^ L) . k = N1 & (<*N*> ^ L) . (k + 1) = N2 & N2 is_succ_of N1 )

take N2 = N2; :: thesis: ex N1, N2 being strict LTLnode of v st
( (<*N*> ^ L) . k = N1 & (<*N*> ^ L) . (k + 1) = N2 & N2 is_succ_of N1 )

thus ex N1, N2 being strict LTLnode of v st
( (<*N*> ^ L) . k = N1 & (<*N*> ^ L) . (k + 1) = N2 & N2 is_succ_of N1 ) by E205, E206, E207; :: thesis: verum
end;
end;
end;
hence ex N1, N2 being strict LTLnode of v st
( (<*N*> ^ L) . k = N1 & (<*N*> ^ L) . (k + 1) = N2 & N2 is_succ_of N1 ) ; :: thesis: verum
end;
hence ex N, M being strict LTLnode of v st
( N = (<*N*> ^ L) . k & M = (<*N*> ^ L) . (k + 1) & M is_succ_of N ) ; :: thesis: verum
end;
hence ex n being Nat ex L being FinSequence ex M being strict LTLnode of v st
( 1 <= n & len L = n & L . 1 = N & L . n = M & the LTLnew of M = {} v & L is_Finseq_for v ) by D5, D6, D7, D3, NAT_1:11; :: thesis: verum
end;
end;
end;
hence ex n being Nat ex L being FinSequence ex M being strict LTLnode of v st
( 1 <= n & len L = n & L . 1 = N & L . n = M & the LTLnew of M = {} v & L is_Finseq_for v ) ; :: thesis: verum
end;
hence ex n being Nat ex L being FinSequence ex M being strict LTLnode of v st
( 1 <= n & len L = n & L . 1 = N & L . n = M & the LTLnew of M = {} v & L is_Finseq_for v ) ; :: thesis: verum
end;
hence ( len N <= l + 1 implies ex n being Nat ex L being FinSequence ex M being strict LTLnode of v st
( 1 <= n & len L = n & L . 1 = N & L . n = M & the LTLnew of M = {} v & L is_Finseq_for v ) ) ; :: thesis: verum
end;
hence S1[l + 1] ; :: thesis: verum
end;
A3: for k being Nat holds S1[k] from NAT_1:sch 2(A1, A2);
set k = len N;
reconsider k = len N as Nat ;
S1[k] by A3;
hence ex n being Nat ex L being FinSequence ex M being strict LTLnode of v st
( 1 <= n & len L = n & L . 1 = N & L . n = M & the LTLnew of M = {} v & L is_Finseq_for v ) ; :: thesis: verum