reserve f for Function;
reserve p,q for FinSequence;
reserve A,B,C for set,x,x1,x2,y,z for object;
reserve k,l,m,n for Nat;
reserve a for Nat;
reserve D for non empty set;
reserve d,d1,d2,d3 for Element of D;
reserve L,M for Element of NAT;

theorem Th33:
  x in rng p & n = x..p - 1 implies p | Seg n = p -| x
proof
  assume x in rng p;
  then ex m st m = x..p - 1 & p | Seg m = p -| x by Def5;
  hence thesis;
end;
