reserve a,b,c for Integer;
reserve i,j,k,l for Nat;
reserve n for Nat;
reserve a,b,c,d,a1,b1,a2,b2,k,l for Integer;
reserve p,p1,q,l for Nat;

theorem Th29:
  not 4 is prime
proof
  ex n st n divides 4 & n<>1 & n<>4
  proof
    take 2;
    4 = 2*2;
    hence thesis;
  end;
  hence thesis;
end;
