Abstract: Non-monotonic reasoning is often used in daily life, e.g. lacking evidence to the contrary of β we infer β. This kind of logic has applications in queries to knowledge bases, very large databases and deductive bases. This case study uses the "Yale Shooting" problem to present non-monotonic reasoning from a proof-theoretic standpoint. Basic knowledge of first order logic and many-sorted algebra is assumed.

Key words: non-monotonic reasoning, Yale shooting problem, logic, axioms, contradiction

摘要： 非单调推理多见于日常生活中。比如，无证据证实B的反面，我们得出结论B。这种逻辑在计算机科学中的知识库、超大数据库和推理库中有许多运用。本案例是著名的“耶鲁枪击案”。据此介绍非单调推理。

关键词: 非单调推理, 耶鲁枪击案, 逻辑, 公理, 悖论