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https://issues.apache.org/jira/browse/RYA-417?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16319376#comment-16319376
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ASF GitHub Bot commented on RYA-417:
------------------------------------
Github user jessehatfield commented on a diff in the pull request:
https://github.com/apache/incubator-rya/pull/255#discussion_r160550347
--- Diff:
extras/rya.forwardchain/src/main/java/org/apache/rya/forwardchain/rule/AntecedentVisitor.java
---
@@ -0,0 +1,51 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.rya.forwardchain.rule;
+
+import java.util.HashSet;
+import java.util.Set;
+
+import org.openrdf.query.algebra.StatementPattern;
+import org.openrdf.query.algebra.helpers.QueryModelVisitorBase;
+
+/**
+ * Query visitor that identifies all triple patterns represented as
+ * {@link StatementPattern}s in a query, which therefore represent triples
+ * that could potentially contribute to a solution. Considers only the
statement
+ * patterns themselves, i.e. the leaves of the query tree, and does not
consider
+ * other constraints that may restrict the set of triples that may be
relevant.
+ * This means relying on this analysis to determine whether a fact can be
part
+ * of a solution can yield false positives, but not false negatives.
+ */
+class AntecedentVisitor extends QueryModelVisitorBase<RuntimeException> {
--- End diff --
Oh, I think I missed that -- looks like the only difference is that it
skips over filter conditions. I think we don't want to skip filter conditions,
here, though -- if the rule is `CONSTRUCT { stuff } WHERE { ?x a :T . FILTER
EXISTS {?x :p :A} }` then the rule should be triggered by either `:x a :T` or
`:x :p :A` .
> Implement a forward-chaining rules engine (SPIN)
> ------------------------------------------------
>
> Key: RYA-417
> URL: https://issues.apache.org/jira/browse/RYA-417
> Project: Rya
> Issue Type: New Feature
> Reporter: Jesse Hatfield
> Assignee: Jesse Hatfield
>
> Implement a forward-chaining reasoner that:
> * Runs as a batch process
> * Operates on user-defined [SPIN|http://spinrdf.org] rules
> * Inserts derived information back into Rya
> * Iterates until no new information can be derived
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