空值环境下的NJD及其推导规则的研究

Research of NJD and its Inference Rules Under Null Circumstances

本文在空值环境下的ＮＦＤ，ＮＭＶＤ强、弱保持条件及相应的推导公理的基础上，讨论了空值环境下的连接依赖的强、弱保持成立的条件及相应的定理。同时，讨论了ＮＪＤ在强、弱保持条件下的推导公理的存在性问题。

In this paper, the tenable condition of the strong and weak holding of join dependency under null value circumstances and the relevant theorems are discussed.The cxistence problem of NJD infer axiom under the condition of strong or weak holding is explained also.