(Since the sub-structure is usually represented in the computer by a set of integer variables with constraints, these problems can be viewed as special cases of constraint satisfaction or discrete optimization; but they are usually formulated and solved in a more abstract setting where the internal representation is not explicitly mentioned.)
（由于子结构通常在计算机中用一组带有约束的整数变量来表示，所以这些问题可以看作是约束满足或离散优化的特例;但它们通常是在一个更抽象的情况下制定和解决的，内部表示没有明确提及。