It expounds the calculting formulas of single mapping and full mapping and explains their application in solving the problem of permutations and combinations.
本文用映射的观点对排列组合问题进行了分析与思考 ,论述了单射个数与满射个数的计算公式及其在一些排列组合问题中的应
The authors obtained some sufficient and necessary conditions of surjective Toeplitz operators,through investigating the symbol of Toeplitz operator.
通过对Toeplitz算子符号的考察,作者得到了满射Toeplitz算子的一些充分和必要的条件,并对某些特殊情形作了详细的刻划,推广了MichaelSand的一个结果。
In the first part of this paper, we got some sufficient and necessary conditions about surjective Toeplitz operators, through investigating symbol of Toeplitz operator via J.
Bourgain分解定理对Toeplitz算子的符号的考察，得到了一些Toeplitz算子满射的充分必要条件。
This article proves that in the homomorphism of G onto ■,the inverse image of a maximal normal subgroup in ■ is also a maximal normal subgroup in G.
本文得到了在同态满射下,极大正规子群的逆象也是极大正规子群,并给出了极大正规子群的象也是极大正规子群的一些等价条件。
This article proved that in the homomorphism of G onto H, the inverse image of a maximal ideal in H is also a maximal ideal in G.
得到了同态满射下,最大理想的逆象是最大理想,并给出了最大理想的象也是最大理想的一些等价条件。