Forgetting in logic programs with ordered disjunction

We present a new forgetting method in logic programs with ordered disjunction (LPODs). To forget a literal means to give it up from the answer sets of the program. There is a known method for doing this in an extended logic program (ELP) by transforming it into another such program whose answer sets have only lost the forgotten literal. However, a naive application of it to an LPOD can produce undesirable results. Our new method avoids these, and ensures that the answer sets of the LPOD, as specified by its so-called split programs, only lose as few literals as are necessary. To achieve this we introduce two new literals "inverted perpendicular" and "perpendicular to" into the syntax of LPODs and extend the definition of an answer set accordingly.