半模是模的概念的推广.显然, 每个模都是一个半模,但反之不然.为了定义一个半模, 采用了半子环,它是从属于环的运算下的环的子集.利用半子环来定义半模,并且证明了半模依赖于所定义的半子环.此外,可以得证,任何一个半模,都能得到不只一个由半模所确定的半子环,还可以定义一个半模的子半模.最后,得到了一个环包含一个半子环的充分必要条件.“,”The concept of demi-modules is a generalization of modules. For clearly every m odule is a demi-module and not conversely. To define a demi-module we make use of a demi-subring which is a subset of a ring closed under both the operations of the ring. Using a demi-subring we define demi-modules and prove the demi- modu les depend on the demi-subring over which it is defined. Further we see that fo r a demi-module we can have more than one demi-subring over which it can be de fined. We also define sub-demi-modules of a demi-module. Finally we obtain a necessary and sufficient condition for a ring to contain a demi-subring.