Suppose M is a left R-module. If the left annihilator of any element of End_R(M) is a direct summand of M, then M is cal设M是左R-模,若End_R(M)中任意元φ在M中的左零化子是M的直和项,则称M是左Richart模;
if the left annihilator of any principal left ideal of End_R(M) is a direct summand of M, then M is called left principa若End_R(M)中任意左主理想I在M中的左零化子是M的直和项,则称M是左主拟-Baer模。