%0 Journal Article
%T Note on Question of Makinson<br>Makinson一个公开问题的注记
%A WU Mao-nian
%A CHEN Wu
%A ZHANG Ming-yi
%A SHEN Fu-xing
%A <br>吴茂念
%A 陈武
%A 张明义
%A 沈复兴
%J 计算机科学
%D 2009
%I 
%X Essential letter in a set of formulae plays an important role.Now it is a focus of research to introduce essential letter into a set of valuations.Makinson formulated an open problem about essential letter in 2005.This paper shows that no letter is essential to nonempty set of valuations V if equivalent valuations in V or not in V.
%K Non-monotonic reasoning
%K Essential letter
%K Equivalent relation<br>非单调推理
%K essential原子
%K 等价关系
%U http://www.alljournals.cn/get_abstract_url.aspx?pcid=5B3AB970F71A803DEACDC0559115BFCF0A068CD97DD29835&cid=8240383F08CE46C8B05036380D75B607&jid=64A12D73428C8B8DBFB978D04DFEB3C1&aid=4C4979AA89072511793C8F85F0AD968B&yid=DE12191FBD62783C&vid=933658645952ED9F&iid=B31275AF3241DB2D&sid=F9F74EC1AA08A7B9&eid=AD16A18DBD734D13&journal_id=1002-137X&journal_name=计算机科学&referenced_num=0&reference_num=9