reserve A,B,C,D,p,q,r for Element of LTLB_WFF,
        F,G,X for Subset of LTLB_WFF,
        M for LTLModel,
        i,j,n for Element of NAT,
        f,f1,f2,g for FinSequence of LTLB_WFF;

theorem Th1:
  M |= F implies M |=0 F
proof
  assume Z1: M |= F;
  let A;
  assume A in F;then
  M |= A by Z1;
  hence M |=0 A;
end;
