Three Typical Properties of Non-mono-tonic Reasoning

This paper presents that, although there are many non-monotonic reasoning schemata different in formal expression and semantics, all of them must have the following three properties.One is the general non-monotonic properties that most of us agree. The second is the undetermination of knowledge increase and the fault tolerance in reasoning. The third is the difficult computation of non-monotonic reasoning, if the correctness and completeness are expected.