reserve k,n,n1,m,m1,m0,h,i,j for Nat,
  a,x,y,X,X1,X2,X3,X4,Y for set;
reserve L,L1,L2 for FinSequence;
reserve F,F1,G,G1,H for LTL-formula;
reserve W,W1,W2 for Subset of Subformulae H;
reserve v for LTL-formula;
reserve N,N1,N2,N10,N20,M for strict LTLnode over v;
reserve w for Element of Inf_seq(AtomicFamily);
reserve R1,R2 for Real_Sequence;

theorem Th35:
  L is_Finseq_for v & 1<= k & k<len(L) implies CastNode(L.(k+1),v)
  is_succ_of CastNode(L.k,v)
proof
  assume L is_Finseq_for v & 1<= k & k<len(L);
  then consider N,M such that
A1: N = L.k and
A2: M=L.(k+1) & M is_succ_of N;
  CastNode(L.k,v) = N by A1,Def16;
  hence thesis by A2,Def16;
end;
