Improved Propositional Extension Rule

Method based on extension rule is a new method for theorem proving, whether or not it will behave well in theorem proving depends on the efficiency. Moreover, the efficiency of propositional extension rule will affect that of first order extension rule directly. Thus the efficiency of the propositional extension rule is very important. ER and IER are two extension rule methods Lin gave. We have improved the ER method before. In order to increase the efficiency of IER, this paper improves IER by some reduction rules. And then the soundness and completeness of it is proved. We also report some preliminary computational results