... control the input and the output. The user can specify whether the input is sorted in ascendingor descending order, and whether null values will be listed at the beginningor at the end, using the ... determines how far the pattern should be advanced in the input, and ACM Transactions on Database Systems, Vol. 29, No. 2, June 2004.Expressing and Optimizing Sequence Queries in Database Systems •295—next( ... φjk. Furthermore, allthe original GPentries in rows up to and including j − 1 remain unchanged, and so are all arcs leading to entries in these rows.Again we assume that the end nodes of...