reserve k,n,m for Nat,
  a,x,X,Y for set,
  D,D1,D2,S for non empty set,
  p,q for FinSequence of NAT;
reserve F,F1,G,G1,H,H1,H2 for LTL-formula;
reserve sq,sq9 for FinSequence;

theorem
  H is_immediate_constituent_of F implies F is negative or F is next or
F is conjunctive or F is disjunctive or F is Until or F is Release;
