reserve x,y,z for object,
  i,j,n,m for Nat,
  D for non empty set,
  s,t for FinSequence,
  a,a1,a2,b1,b2,d for Element of D,
  p, p1,p2,q,r for FinSequence of D;

theorem Th1:
  <*<*d*>*> is tabular
proof
  take n = 1;
  let x;
  assume
A1: x in rng <*<*d*>*>;
A2: len <*d*> = n by FINSEQ_1:39;
  rng <*<*d*>*> = {<*d*>} by FINSEQ_1:38;
  then x = <*d*> by A1,TARSKI:def 1;
  hence thesis by A2;
end;
