theorem
  w |= 'X' v implies w |= * (init v)
proof
  assume
A1: w |= 'X' v;
  for H be LTL-formula st H in 'X' CastLTL(Seed v) holds w|= H
  proof
    let H being LTL-formula;
    assume H in 'X' CastLTL(Seed v);
    then
    ex x being LTL-formula st H=x & ex u being LTL-formula st u in CastLTL(
    Seed v) & x='X' u;
    hence thesis by A1,TARSKI:def 1;
  end;
  hence thesis;
end;
