[Virtuoso-users] Incorrect query results with property paths and variable graphs (VOS 7.10.3207 Windows)

[Dominic Robinson]

Hi

I am using Virtuoso Open Source Edition Version: 07.10.3207, Build: Feb
17 2014 running on Windows 7.

I am seeing some strange, incorrect(?), results when using aggregates
and property paths.  In the process of trying to generate a small
example case, I have come across the following related problem.

I am seeing different results using different forms of property paths
depending on whether I specify a no graph, an explicit graph or a
variable graph.

Given a data set created like this:

prefix d: <http://foo/>
drop silent graph <http://foo>
insert into <http://foo>
{
        d:top d:level "top".

        d:m d:in d:top.

        d:a d:in d:m;
        d:item "a";
        d:value 0 .
  
        d:b d:in d:m;
        d:item "b";
        d:value 1 .

        d:c d:in d:m;
        d:item "c";
        d:value 1 .
}

The queries below demonstrate different results:


##########################################
# No graph - correct

prefix d: <http://foo/>
select *
where
{
  ?item d:value ?value.
  ?item d:in+ ?top.
  ?top d:level ?level.  
}

returns: (CORRECT)

http://foo/a     0      http://foo/top  "top"
http://foo/b     1       http://foo/top  "top"
http://foo/c     1       http://foo/top " top"

##########################################
# Explicit graph - correct

prefix d: <http://foo/>
select *
where
{
  graph <http://foo> {
  ?item d:value ?value.
  
  ?item d:in+ ?top.
  ?top d:level ?level.  
  }
}

returns:(CORRECT)

http://foo/b    1        http://foo/top         "top"
http://foo/a     0       http://foo/top  "top"
http://foo/c     1       http://foo/top  "top"

##########################################
# Variable graph version 1 - incorrect

prefix d: <http://foo/>
select *
where
{
  graph ?g {
  ?item d:value ?value.
  
  ?item d:in+ ?top.
  ?top d:level ?level.  
  }
}

returns: (INCORRECT)

http://foo      http://foo/a    0        http://foo/top         "top"
http://foo       http://foo/a    0       http://foo/top  "top"

##########################################
# Variable graph version 2 - incorrect

prefix d: <http://foo/>
select *
where
{
  graph ?g {
  ?item d:value ?value.
  ?item d:in{2} ?top.
  ?top d:level ?level.  
  }
}

returns: (INCORRECT)

http://foo      http://foo/a    0       http://foo/top   "top"

##########################################
# Variable graph version 3 - correct

prefix d: <http://foo/>
select *
where
{
  graph ?g {
  ?item d:value ?value.
  ?item d:in/d:in ?top.
  ?top d:level ?level.  
  }
}

returns: (CORRECT)

http://foo      http://foo/a    0       http://foo/top  "top"
http://foo       http://foo/b    1      http://foo/top   "top"
http://foo       http://foo/c    1      http://foo/top   "top"


The three different variations on the property path all seem to work
when the graph is not specified or when it is specified explicitly. 

Best regards

Dominic Robinson

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