[jira] [Commented] (RYA-293) Implement owl:unionOf inference

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/RYA-293?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16095537#comment-16095537 ] 

ASF GitHub Bot commented on RYA-293:
------------------------------------

GitHub user jessehatfield opened a pull request:

    https://github.com/apache/incubator-rya/pull/180

    RYA-293 Added owl:unionOf inference

    If A is the union of B and C, then B and C are subclasses of A.
    
    A owl:unionOf (B C D) means that A is the exact set of nodes that belong to any of B, C, and/or D. Therefore:
    1. Any node belonging to B is implied to belong to A, any node belonging to C is implied to belong to A, and any node belonging to node D is implied to belong to A. This is the same implication as B rdfs:subClassOf A, C rdfs:subClassOf A, rdfs:subClassOf A, so we handle this by adding these edges to the subclass graph. (Equivalent to *scm-uni* from [this list of rules](https://www.w3.org/TR/owl2-profiles/#Reasoning_in_OWL_2_RL_and_RDF_Graphs_using_Rules).)
    
    2. Any node belonging to A is implied to belong to at least one of B, C, or D. However, we currently lack the advanced reasoning that would be needed to meaningfully apply this to a query (e.g. using some additional schema about B and C to prove by contradiction that the node must belong to D), so this implication is ignored for now.
    
    (This limitation is consistent with the three OWL 2 profiles: EL and QL do not support unionOf and RL only supports the first case.)
    
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    ## Description
    >What Changed?
    After creating the initial subClassOf graph, the inference engine then checks for any owl:unionOf triples. For each one, the object should refer to the head of a list and the subject is a type representing the union of all the list elements. Traverse the list and add an edge to the subClassOf graph for every member: since anything belonging to the list element belongs to the union type, we can also say that the list element is a subClassOf the union type.
    
    ### Tests
    InferenceEngineTest.testUnionOf inserts schema including unions and verifies that the InferenceEngine builds the correct subClassOf graph.
    InferenceIT.testUnionQuery inserts schema and ontology, refreshes the InferenceEngine, executes a query relying on union types, and verifies that the expected results are returned.
    
    ### Links
    [Jira](https://issues.apache.org/jira/browse/RYA-293)
    
    ### Checklist
    - [ ] Code Review
    - [ ] Squash Commits
    
    #### People To Review
    @meiercaleb
    @isper3at
    @ejwhite922

You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/jessehatfield/incubator-rya RYA-293-unionOf-inference

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/incubator-rya/pull/180.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #180
    
----
commit ee538a9b113312d29927b0e61bb7396e35e112c5
Author: Jesse Hatfield <je...@parsons.com>
Date:   2017-07-20T22:48:24Z

    RYA-293 Added owl:unionOf inference
    
    If A is the union of B and C, then B and C are subclasses of A.

----


> Implement owl:unionOf inference
> -------------------------------
>
>                 Key: RYA-293
>                 URL: https://issues.apache.org/jira/browse/RYA-293
>             Project: Rya
>          Issue Type: Sub-task
>          Components: sail
>            Reporter: Jesse Hatfield
>            Assignee: Jesse Hatfield
>
> An *{{owl:unionOf}}* expression defines one type to be equivalent to the union of another set of types. If the ontology states that {{:Parent}} is the union of {{:Mother}} and {{:Father}}, then the inference engine should rewrite statement patterns of the form {{?x rdf:type :Parent}} to check for resources that are stated to be any of the types {{:Mother}}, {{:Father}}, or {{:Parent}}.



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