幂等

This paper is a study on the invertibility of the commutator of scalar-idempotent elements and scalar-involutory elements of a unitary ring.

本文一有单位元的环中倍等元的换位子与倍对合元的换位子的可逆性问题。

The necessary and sufficient conditions of similarity of two idempotent matrices are proved, the idempotency of linear combinations of two idempotent matrices is discussed.

摘要证明数域上同阶等阵相似的充要条件是它们有相同的秩；给出等阵的相似标准型；讨论等阵的线性组合仍是等阵的充要条件。