SPARQL Rule with reasoning does not work

Support
1

Hello All,

I am a newbie to Stardog DB and try to use the Rule and the reasoning feature of Stardog. I expect from enabling the reasoning and using the following simple rule to update values of individuals matching to the IF condition. It does happening. I will truly appreciate if you can help me.
Here is the simple rule that tries to update the state of a ?x based on the state of another object ?p.
I added the rule to the database and the web interface for database browsing shows it as a SPARQLRule. I also enabled reasoning and chose the SL reasoning algorithm.

IF {	?x a :Path.
        ?x   :hasActive  ?p.
	?p  :hasState ?s.
	BIND ( ?s AS ?state).

    }
    THEN {
        ?x  :hasState ?state .
    }

Thanks in advance!

2

Hi,

Please share the query you are executing, the expected results and the actual results.

Jess

3

Hi Jess,
Thanks for your reply,
I am not running any query, I am under the impression of this rule will fire whenever any changes in the db are happening and I expect it updates the ?X state with the state of ?P. To test if it works, I simply change the state of the ?P to “Inactive” and expect ?X :hasState "active" changes to ?X :hasState "Inactive" automaticlly.

BR,

4

Hi,

It sounds like you are expecting the rules to materialize triples and act as sort of a "trigger." Stardog does not perform materialization; we perform Query Rewriting at query runtime.

In short, If you run the query select * where {?x :hasState "active"}, it will give you all of the entities that either explicitly have that triple in the db, or for which the rule applies. Instead of looking for ?X :hasState "Inactive" in the database, try running the query above, changing a state, and running it again. You should see the results you're looking for.

5

Hi,
Thanks for your reply, I can see the expected results by running the query (1): select * where {?x :hasState “Inactive”}, however, if I run the select * where {?x :hasState “active”} query it also returns the triples supposed to be “Inactive” ! I guess this time it is because of it has explicit value of “active” . It is a preplex behaviour to me, is there anyway that I can get more consistent outputs?
Thanks !

6

The rule does exactly what’s stated there. It matches the data and produces new data. If a path has both states, indeed this will be inferred.

But to be honest, without seeing the data it’s impossible to help you further. Can you share the sample data please?

7

Thanks for your reply,
You can find a simplified data set from test-arsham-w-const-2-1.ttl (2.3 KB)
For this data set, if I run the query: SELECT * WHERE {?p a of:Path; of:hasState 'Inactive'} returns Nil if the reasoning is OFF and return the three paths if the reasoning is ON as it should be. However, If I run SELECT * WHERE {?p a of:Path; of:hasState 'active'} it always (with/without reasoning) return the same three defined paths.

If I change the rule to the one mentioned in the previous post, it did not work at all. I have to specify the value for the Dataproperty :hasState to make it work as described.

Many Thanks for help!

8

Hi,

With your dataset I was able to play around with the rules/queries and sort of get what I think you’re looking for.

I removed ALL of the of:hasState triples from the of:Paths, keeping them just on the of:AvailPaths. I then added the following rule:

[] a <tag:stardog:api:rule:SPARQLRule> ;
	<tag:stardog:api:rule:content> """IF {	
            ?x a of:Path.    
            ?x  of:hasActive/of:hasState \"active\".
          }    
          THEN {        
            ?x  of:hasState \"active\".    
          }""" .

This allows me to query the “active” Paths like so:

> stardog query -r myDb "select ?p {?p a of:Path ; of:hasState \"active\"}"
+---------------------------------------------+
|                      p                      |
+---------------------------------------------+
| of:path_00:00:00:00:00:01_00:00:00:00:00:03 |
+---------------------------------------------+

And the “Inactive” Paths like so:

> stardog query -r myDb "select ?p {?p a of:Path . MINUS {?p of:hasState \"active\"}}"
+---------------------------------------------+
|                      p                      |
+---------------------------------------------+
| of:path_00:00:00:00:00:01_00:00:00:00:00:04 |
| of:path_00:00:00:00:00:01_00:00:00:00:00:02 |
+---------------------------------------------+

While it doesn’t reason out an “Inactive” triple, it does honor the logic of showing you of:Paths that are NOT “active”

9

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