Yong Liu Congfu Xu Qiong Zhang Yunhe Pan Rough Rule Extracting From Various Conditions: Incremental and Approximate Approaches for Inconsistent Data. 403-427 2008 84 Fundam. Inform. 3-4 http://iospress.metapress.com/content/m7k3122n468748x1/ db/journals/fuin/fuin84.html#LiuXZP08