[JENA-1021] Odd MINUS behavior in a UNION

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: Jena 3.0.0
• Fix Version/s: Jena 3.0.1
• Component/s: Jena
• Assignee: Andy Seaborne
• Reporter: William Tritchler
• Created: 04/Sep/15 22:17
• Updated: 12/Dec/15 17:46
• Resolved: 22/Sep/15 12:13

Description

Given the sample data:

@prefix owl:    <http://www.w3.org/2002/07/owl#>
@prefix rdfs:   <http://www.w3.org/2000/01/rdf-schema#> .
@prefix :       <http://no.such.org/test#> .

<urn:test:node1>
    a :TestNode ;
    rdfs:label "Node 1" .

<urn:test:node2>
    a :TestNode ;
    rdfs:label "Node 2" .

:TestNode
  a owl:Class ;
  rdfs:label "Test Node" .

When I run the union query:

PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX app: <http://no.such.org/test#>
 
select distinct ?id where {
  ?id a app:TestNode .
  {
    ?id rdfs:label "Node 1" .
    minus { ?id a app:TestNode }
  } union {
    ?id rdfs:label "Node 1" .
    minus { ?id a app:TestNode }
  }
}

Observed:
The query unexpectedly returns a single value: <urn:test:node1>

Expected:
The query should return no results.

Unless, of course, I'm totally off-base here. I suspect an issue, since removing the union and having a single:

  {
    ?id rdfs:label "Node 1" .
    minus { ?id a app:TestNode }
  }

returns the expected empty result set.

Issue Links

• relates to: JENA-1028 2.3.1-snapshot fails with OpDisjunction / org.apache.jena.atlas.lib.NotImplemented