Fabian Meyer created DROOLS-1001: ------------------------------------ Summary: Tabled Logic Programming-like mechanism to avoid infinite query recursion Key: DROOLS-1001 URL: https://issues.jboss.org/browse/DROOLS-1001 Project: Drools Issue Type: Feature Request Reporter: Fabian Meyer Assignee: Mark Proctor Priority: Optional Queries, such as a transitive closure, will lead to an infinite query recursion in PHREAK: {code:drl} declare Resource name : String @key end declare partOf subject : Resource @key object : Resource @key end rule "init" when then Resource a = new Resource("a"); Resource b = new Resource("b"); Resource c = new Resource("c"); insert (new partOf(a,b)); insert (new partOf(a,c)); end rule "print container" when trans_partOf(part, container;) then System.out.println(part + " partOf " + container); end query trans_partOf(Resource part, Resource container) // Find direct asserted fact partOf(part,container;) or // Find the transitive closure trans_partOf(part, p;) and trans_partOf(p, container;) end {code} The algorithm can easily be rewritten as a production rule, resulting in a huge amount of materialized facts in large knowledge bases, which are probably never needed. In Logic Programming, a mechanism called Tabled Logic Programming is used to avoid such infinite recursion. Maybe the tabling mechanism can be adapted to PHREAK, in order to avoid fact materilization when using production rules instead of queries. -- This message was sent by Atlassian JIRA (v6.4.11#64026)