Emma hansson ： no , the us does not offer 预科 like australia and uk 问：美国大学有没有预科，什么条件才需要读预科？
2.
In the former category , the best known is agm theory which is a milestone in this field . in the latter category , nebel , fuhrmann and hansson may be representative persons who suggest studying changes of base - generated belief sets . recently , bochman has introduced a framework of belief change in which both agm theory and the theory of base change can be reconstructed by defining appropriate operations on the associated epistemic states 最近，以色列著名人工智能学者bochman建立了一种一般的信念变化理论框架，这种框架试图将表示信念变化的两种最主要的方法，即，信念变化的agm理论以及信念变化的基表示理论的共同特征融入其中，使之能够成为信念变化理论研究的一个共同的平台。
