The present paper investigates an abductive framework in default logic, and gives a solving abduction method in propositional default theories. 摘要研究缺省逻辑表示下的溯因框架，给出一种基于规则的命题逻辑缺省溯因诊断的求解方法。
Propositional variables are the basic building-blocks of propositional formulas, used in propositional logic and higher logics. 命题变量是命题公式的基本构件板块，用于命题逻辑和更高的逻辑中。
