
theorem Th7:
  for i,j being Integer,
      p being Prime
  st p divides i * j holds p divides i or p divides j
proof
let i,j be Integer,
    p be Prime;
assume A1: p divides i * j;
assume not(p divides i);
then i gcd p = 1 by Th6;
hence thesis by A1,INT_2:25,INT_2:def 3;
end;
