Answering queries using views with arithmetic comparisons

摘要: We consider the problem of answering queries using views, where and views are conjunctive with arithmetic comparisons (CQACs) over dense orders. Previous work only considered limited variants this problem, without giving a complete solution. have developed novel algorithm to obtain maximally-contained rewritings (MCRs) for having left (or right) semi-interval-comparison predicates. For semi-interval queries, we show that language finite unions CQAC is not sufficient find solution, identify cases datalog sufficient. Finally, it decidable equivalent queries.