reserve m, n for Nat;

theorem Th22:
  1 is square-free
proof
  assume 1 is square-containing;
  then consider n being Prime such that
A1: n |^ 2 divides 1;
  n * n divides 1 by A1,WSIERP_1:1;
  then n = 1 or n = -1 by WSIERP_1:15,XCMPLX_1:182;
  hence contradiction by INT_2:def 4;
end;
