reserve X for set;
reserve a,b,c,k,m,n for Nat;
reserve i,j for Integer;
reserve r,s for Real;
reserve p,p1,p2,p3 for Prime;

theorem Th54:
  14|^2 - 1 = 3*5*13
  proof
    14|^2 = 14*14 by WSIERP_1:1;
    hence thesis;
  end;
