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Multiple statements query SPARQL 1.1 property-paths Virtuoso 7.2.X

由 假装没事ソ 提交于 2020-01-06 20:25:17

问题


A sample RDF dataset has entries owl#NamedIndividual grouped by owl#Class and a custom relation named IsMemberOf. When I try to obtain a list of results segregated by their type, it works well but the moment I add a way to obtain their corresponding IsMemberOf I don't get expected results.

Here is three SPARQL 1.1 queries I gave to Virtuoso (sample dataset below):

Query 1

sparql select * from <test>
where {
#If I uncomment the next line I don't get the proper results
#  ?s <IsMemberOf> ?member_of.
  ?s rdfs:label ?name.
  {
    ?s rdf:type/rdfs:subClassOf* <livingthings>.
  } UNION {
    ?s a <rock>.
  }
};

Query 2

sparql select * from <test>
where {
#If I uncomment the next line I get no results at all
#   ?s <IsMemberOf> ?member_of.
    ?s rdfs:label ?name.
    ?s rdf:type/rdfs:subClassOf* <livingthings>.
};

Query 3

sparql select * from <test>
where {
  ?s <IsMemberOf> ?member_of.
  ?s rdfs:label ?name.
  ?s rdf:type <dog>.
#If I replace the previous line with the next line I get no results at all
# ?s rdf:type/rdfs:subClassOf* <livingthings>.
};

This is how the data is grouped:

livingthings
->mammal
--->dog
----->doggy_the_dog
----->fido_the_dog
--->cat
---->katy_the_cat
--->elephant
----->eli_the_elephant
->reptile
--->snake
----->snakey_the_snake
nonlivingthings
->rock
--->rocky_the_rock
--->ralf_the_rock

group_a
->rocky_the_rock
->ralf_the_rock
->snakey_the_snake
->doggy_the_dog
group_b
->fido_the_dog
->katy_the_cat
group_c
->eli_the_elephant

Finaly here is the data I used

sparql create silent graph <test>;
sparql insert into graph <test> {
  <nonlivingthings> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/2002/07/owl#Class>.
  <nonlivingthings> <http://www.w3.org/2000/01/rdf-schema#label> "Non-living things".
  <rock> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/2002/07/owl#Class>.
  <rock> <http://www.w3.org/2000/01/rdf-schema#label> "Rock".
  <rock> <http://www.w3.org/2000/01/rdf-schema#subClassOf> <nonlivingthings>.
  <rocky_the_rock> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/2002/07/owl#NamedIndividual>.
  <rocky_the_rock> <IsMemberOf> <group_a>.
  <rocky_the_rock> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <rock>.
  <rocky_the_rock> <http://www.w3.org/2000/01/rdf-schema#label> "Rocky the rock".
  <ralf_the_rock> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/2002/07/owl#NamedIndividual>.
  <ralf_the_rock> <IsMemberOf> <group_a>.
  <ralf_the_rock> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <rock>.
  <ralf_the_rock> <http://www.w3.org/2000/01/rdf-schema#label> "Ralf the rock".  
  <livingthings> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/2002/07/owl#Class>.
  <livingthings> <http://www.w3.org/2000/01/rdf-schema#label> "Living things".
  <mammal> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/2002/07/owl#Class>.
  <mammal> <http://www.w3.org/2000/01/rdf-schema#label> "Mammal".
  <mammal> <http://www.w3.org/2000/01/rdf-schema#subClassOf> <livingthings>.
  <reptile> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/2002/07/owl#Class>.
  <reptile> <http://www.w3.org/2000/01/rdf-schema#label> "Reptile".
  <reptile> <http://www.w3.org/2000/01/rdf-schema#subClassOf> <livingthings>.
  <dog> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/2002/07/owl#Class>.
  <dog> <http://www.w3.org/2000/01/rdf-schema#label> "Dog".
  <dog> <http://www.w3.org/2000/01/rdf-schema#subClassOf> <mammal>.
  <cat> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/2002/07/owl#Class>.
  <cat> <http://www.w3.org/2000/01/rdf-schema#label> "Cat".
  <cat> <http://www.w3.org/2000/01/rdf-schema#subClassOf> <mammal>.
  <elephant> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/2002/07/owl#Class>.
  <elephant> <http://www.w3.org/2000/01/rdf-schema#label> "Elephant".
  <elephant> <http://www.w3.org/2000/01/rdf-schema#subClassOf> <mammal>.
  <snake> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/2002/07/owl#Class>.
  <snake> <http://www.w3.org/2000/01/rdf-schema#label> "Snake".
  <snake> <http://www.w3.org/2000/01/rdf-schema#subClassOf> <reptile>.
  <snakey_the_snake> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/2002/07/owl#NamedIndividual>.
  <snakey_the_snake> <IsMemberOf> <group_a>.
  <snakey_the_snake> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <snake>.
  <snakey_the_snake> <http://www.w3.org/2000/01/rdf-schema#label> "Snakey the snake".
  <doggy_the_dog> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/2002/07/owl#NamedIndividual>.
  <doggy_the_dog> <IsMemberOf> <group_a>.
  <doggy_the_dog> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <dog>.
  <doggy_the_dog> <http://www.w3.org/2000/01/rdf-schema#label> "Doggy the dog".
  <fido_the_dog> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/2002/07/owl#NamedIndividual>.
  <fido_the_dog> <IsMemberOf> <group_b>.
  <fido_the_dog> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <dog>.
  <fido_the_dog> <http://www.w3.org/2000/01/rdf-schema#label> "Fido the dog".
  <katy_the_cat> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/2002/07/owl#NamedIndividual>.
  <katy_the_cat> <IsMemberOf> <group_b>.
  <katy_the_cat> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <cat>.
  <katy_the_cat> <http://www.w3.org/2000/01/rdf-schema#label> "Katy the cat".
  <eli_the_elephant> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/2002/07/owl#NamedIndividual>.
  <eli_the_elephant> <IsMemberOf> <group_c>.
  <eli_the_elephant> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <elephant>.
  <eli_the_elephant> <http://www.w3.org/2000/01/rdf-schema#label> "Eli the elephant".
};

Why do I only get the following incomplet result when I uncomment ?s <IsMemberOf> ?member_of. in query one?

s               member_of   name
rocky_the_rock  group_a     Rocky the rock
ralf_the_rock   group_a     Ralf the rock

All of the results under the <livingthings> class are left out. Is it because of a bug in Virtuoso or the way my SPARQL query is formed?


回答1:


Virtuoso seems to handle user defined relation oddly in a query when mixed with a property path.

Here is the Virtuoso specific way to address this issue.

Query 1 answer

sparql select * from <test>
where {
  ?s rdfs:label ?name.
  {
    ?s <IsMemberOf>{1} ?member_of.
    ?s rdf:type/rdfs:subClassOf* <livingthings>.
  } UNION {
    ?s <IsMemberOf>{1} ?member_of.
    ?s a <rock>.
  }
};

Query 2 answer

sparql select * from <test>
where {
    ?s <IsMemberOf>{1} ?member_of.
    ?s rdfs:label ?name.
    ?s rdf:type/rdfs:subClassOf* <livingthings>.
};

Applying an explicit property path for the user defined relation as such ?s <IsMemberOf>{1} ?member_of. gives the expected results.

In query one the line ?s <IsMemberOf>{1} ?member_of. is applied to each term inside each union element. If not then the results are not as desired. It does solve the issue but it is a bit nonsensical. That is why I'll leave the question open for a few days to see if anyone can provide logical explanation to why things are that way in Virtuoso. If it's just a bug I'll contact them via their mailing list.




回答2:


It's tough to say exactly what the problem here is. The queries you've shown aren't legal SPARQL by themselves (e.g., in SPARQL you do select ..., not sparql select ...;), but that might be the Virtuoso interface you're using. Another possible issue is that <IsMemberOf> and similar are relative IRIs, and how they get resolved may be different between the data loading and the query processing, etc., so it's not necessarily the case that <IsMemberOf> in one place actually refers to the same IRI that <IsMemberOf> refers to in another. You really should use absolute IRIs. I don't know whether or not that's the problem here.

That said, I took your data and resolved the IRIs against http://example.org/ so that they're all absolute, and it looks like the queries work the way you'd want them to. E.g., running the following queries with Jena works just fine.

base <http://example.org/>
prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>

select * where {
  ?s <IsMemberOf> ?member_of.
  ?s rdfs:label ?name.
  ?s a/rdfs:subClassOf* <livingthings>.
}

-------------------------------------------------------
| s                  | member_of | name               |
=======================================================
| <doggy_the_dog>    | <group_a> | "Doggy the dog"    |
| <eli_the_elephant> | <group_c> | "Eli the elephant" |
| <fido_the_dog>     | <group_b> | "Fido the dog"     |
| <katy_the_cat>     | <group_b> | "Katy the cat"     |
| <snakey_the_snake> | <group_a> | "Snakey the snake" |
-------------------------------------------------------

Here's the updated data:

<http://example.org/elephant>
        a       <http://www.w3.org/2002/07/owl#Class> ;
        <http://www.w3.org/2000/01/rdf-schema#label>
                "Elephant" ;
        <http://www.w3.org/2000/01/rdf-schema#subClassOf>
                <http://example.org/mammal> .

<http://example.org/snakey_the_snake>
        a       <http://www.w3.org/2002/07/owl#NamedIndividual> , <http://example.org/snake> ;
        <http://www.w3.org/2000/01/rdf-schema#label>
                "Snakey the snake" ;
        <http://example.org/IsMemberOf>
                <http://example.org/group_a> .

<http://example.org/cat>
        a       <http://www.w3.org/2002/07/owl#Class> ;
        <http://www.w3.org/2000/01/rdf-schema#label>
                "Cat" ;
        <http://www.w3.org/2000/01/rdf-schema#subClassOf>
                <http://example.org/mammal> .

<http://example.org/mammal>
        a       <http://www.w3.org/2002/07/owl#Class> ;
        <http://www.w3.org/2000/01/rdf-schema#label>
                "Mammal" ;
        <http://www.w3.org/2000/01/rdf-schema#subClassOf>
                <http://example.org/livingthings> .

<http://example.org/katy_the_cat>
        a       <http://www.w3.org/2002/07/owl#NamedIndividual> , <http://example.org/cat> ;
        <http://www.w3.org/2000/01/rdf-schema#label>
                "Katy the cat" ;
        <http://example.org/IsMemberOf>
                <http://example.org/group_b> .

<http://example.org/fido_the_dog>
        a       <http://www.w3.org/2002/07/owl#NamedIndividual> , <http://example.org/dog> ;
        <http://www.w3.org/2000/01/rdf-schema#label>
                "Fido the dog" ;
        <http://example.org/IsMemberOf>
                <http://example.org/group_b> .

<http://example.org/dog>
        a       <http://www.w3.org/2002/07/owl#Class> ;
        <http://www.w3.org/2000/01/rdf-schema#label>
                "Dog" ;
        <http://www.w3.org/2000/01/rdf-schema#subClassOf>
                <http://example.org/mammal> .

<http://example.org/eli_the_elephant>
        a       <http://www.w3.org/2002/07/owl#NamedIndividual> , <http://example.org/elephant> ;
        <http://www.w3.org/2000/01/rdf-schema#label>
                "Eli the elephant" ;
        <http://example.org/IsMemberOf>
                <http://example.org/group_c> .

<http://example.org/reptile>
        a       <http://www.w3.org/2002/07/owl#Class> ;
        <http://www.w3.org/2000/01/rdf-schema#label>
                "Reptile" ;
        <http://www.w3.org/2000/01/rdf-schema#subClassOf>
                <http://example.org/livingthings> .

<http://example.org/nonlivingthings>
        a       <http://www.w3.org/2002/07/owl#Class> ;
        <http://www.w3.org/2000/01/rdf-schema#label>
                "Non-living things" .

<http://example.org/livingthings>
        a       <http://www.w3.org/2002/07/owl#Class> ;
        <http://www.w3.org/2000/01/rdf-schema#label>
                "Living things" .

<http://example.org/doggy_the_dog>
        a       <http://www.w3.org/2002/07/owl#NamedIndividual> , <http://example.org/dog> ;
        <http://www.w3.org/2000/01/rdf-schema#label>
                "Doggy the dog" ;
        <http://example.org/IsMemberOf>
                <http://example.org/group_a> .

<http://example.org/rocky_the_rock>
        a       <http://www.w3.org/2002/07/owl#NamedIndividual> , <http://example.org/rock> ;
        <http://www.w3.org/2000/01/rdf-schema#label>
                "Rocky the rock" ;
        <http://example.org/IsMemberOf>
                <http://example.org/group_a> .

<http://example.org/rock>
        a       <http://www.w3.org/2002/07/owl#Class> ;
        <http://www.w3.org/2000/01/rdf-schema#label>
                "Rock" ;
        <http://www.w3.org/2000/01/rdf-schema#subClassOf>
                <http://example.org/nonlivingthings> .

<http://example.org/ralf_the_rock>
        a       <http://www.w3.org/2002/07/owl#NamedIndividual> , <http://example.org/rock> ;
        <http://www.w3.org/2000/01/rdf-schema#label>
                "Ralf the rock" ;
        <http://example.org/IsMemberOf>
                <http://example.org/group_a> .

<http://example.org/snake>
        a       <http://www.w3.org/2002/07/owl#Class> ;
        <http://www.w3.org/2000/01/rdf-schema#label>
                "Snake" ;
        <http://www.w3.org/2000/01/rdf-schema#subClassOf>
                <http://example.org/reptile> .


来源：https://stackoverflow.com/questions/31565565/multiple-statements-query-sparql-1-1-property-paths-virtuoso-7-2-x

标签
rdf
sparql
virtuoso
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