subclasses

This method should be overridden by subclasses.

这个方法应该被子类重写.

Both MAX ( 1) and MARG ( 1) are subclasses of the minimal unsatisfiable formulas, and formulas in these subclasses can be represented by trees.

MAX（1）和MARG（1）是极小不可满足公式的两个子类，这两个子类中的公式可以用树表示。

For the subclasses MAX and MARG of minimal unsatisfiable formulas, we show that the variable and literal renaming problems are equivalent to the graph isomorphism problem GI.

对于极小不可满足公式的子类MAX和MARG，我们证明了：其变元改名和文字改名的复杂性等价于图同构问题GI。

Only the class that defines a signal and its subclasses can emit the signal.

只有定义了信号的类及其子类能够激发信号.