reserve n,i,j,k for Nat;
reserve T for TuringStr,
  s for All-State of T;

theorem Th15:
  for T being TuringStr,t be Tape of T, s,n be Element of NAT st t
  storeData <*s,n*> holds t is_1_between s,s+n+2
proof
  let T be TuringStr,t be Tape of T,s,n be Element of NAT;
  set f=<*s,n*>;
  assume
A1: t storeData f;
A2: len f=2 by FINSEQ_1:44;
  Sum Prefix(f,1)+2*(1-1)=s & Sum Prefix(f,1+1)+2*1=s+n+2 by Th4;
  hence thesis by A1,A2;
end;
