Hi
Thanks again.
Hear you.
I think this is becoming a bit too meta perhaps. Maybe there’s a couple of ways
to go forward.
a. Anybody is a taker to hold me by the hand and use this thread to come up
with a complete cycle for making a new built in and adding it to my fuseki? If
somebody has the time to do this---and I’m happy that it takes what it takes, I
can’t on my end make it a high priority--, we could reuse the thread for the
purpose of a detailed how-to for noobs like me.
b. I think I actually tried the rule below and I didn’t get any inference
result. Don’t know if it’s my config, my rule or my data. I could start a. by
trying to provide a dataset and config file as well. Again, anybody willing to
hold my hand?
Give a shout.
Thanks,
Pierre
From: Lorenz B. [mailto:buehm...@informatik.uni-leipzig.de]
Sent: 17 May 2019 07:24
To: users@jena.apache.org
Subject: Re: Documentation/tutorial on using dates in Jena rules with
GenericRuleReasoner
Hi,
Hi Lorenz,
Thank you for your answer.
Quick follow up.
I think the issue for me is the documentation of the built-ins is too abstract
or relies on understanding the source code. So I suppose, documentation /
tutorial seems somewhat superfluous when you can do that – only I can’t
understand what’s there and the source at the moment.
I can see that it might be too abstract for people coming from different
areas, sure. But, the question is who is able to provide such a tutorial
and also who has the time. It's always a trade-off in Open Source
projects like Jena - I guess most of the devs or other project related
people here are not getting payed, and clearly such a tutorial for most
if not all of the built-ins definitely needs some effort. Ideally, the
community could take over those things, but looks like nobody ever wrote
blog posts or tutorials about the Jena rule system and its built-ins.
1. Yes, I seem to understand difference is a no go but I was wondering if there
might be some work around coercing the dateTime to something else. I’m not sure
I understood that very well but it looks like I can’t use functions in
arguments of built-ins (so no xsd:year(?date) or whatever).
I don't think you can use functions or expressions from the SPARQL
engine resp. its XPath constructors. Both are totally different
implementations I guess - but again, I'm not a developer, so I can't
make a valid statement, except for looking into the code and the docs.
From my point of view, only the mentioned built-ins from the docs are
valid so far.
But then, on greaterThan, something should be workable if I have xsd:dateTime,
no?
What’s wrong with :
[ruleMissedDeadline2:
(?conference ns:hasDeadline ?date)
now(?now)
greaterThan(?now, ?date)
->
(?conference ns:status ns:DeadlinePassed)
]
Well I was clearly thinking too complicated, so yes, your rule should
work given that the docs say
lessThan(?x, ?y), greaterThan(?x, ?y)
le(?x, ?y), ge(?x, ?y)
Test if x is <, >, <= or >= y. Only passes if both x and y are numbers
or time instants (can be integer or floating point or XSDDateTime).
I was more thinking about things like inferring the age of a person
isn't possible right now, but would clearly be some nice to have feature
such that you could have it as implicit fact in your KB without the need
to change the asserted data every year.
2. When you say extend the rule system, you mean adding a class using as a
starting point something is in ..rulesys.builtins and adapting it and then
rebuild all the jars. I’m using Fuseki, so I’d have to rebuild that too, yeah?
Aside from the fact I’m not coding in java, this isn’t the easiest path for me
at the moment.
That's also something I can't answer properly. I mean, yes, you can
create custom built-ins and register those or maybe create an overriding
registry [1] ? But not sure, it looks like at least the overriding
registry would have to be used by the rule parser, so I don't know how
you would have to combine it with Fuseki. And in the end, yes, you have
to repackage Fuseki I think as long as you modify the existing
BuiltinRegistry.
Maybe there is also some other kind of plugin system here, but that can
only be answered by Andy, Dave, Adam, etc.
[1]
https://issues.apache.org/jira/browse/JENA-1204<https://issues.apache.org/jira/browse/JENA-1204>
Many thanks,
Pierre
From: Lorenz B. [mailto:buehm...@informatik.uni-leipzig.de]
Sent: 16 May 2019 08:33
To: users@jena.apache.org
Subject: Re: Documentation/tutorial on using dates in Jena rules with
GenericRuleReasoner
I'm not aware of any tutorial, but afaik you can't do what you did here
with SPARQL in Jena rules without writing custom built-ins or by
extending the existing ones because:
* the "difference" built-in does only work for numbers right now [1]
* there is no support for duration type at all it looks like
So, so far you could only compare datetime values via lessThan, le,
greaterThan, ge but there is no other built-in with support for date
values so far. Others might indeed correct me if I'm wrong of.
It looks like, you have to extend the rule system by custom built-ins -
it's not that difficult though [2]
[1]
https://github.com/apache/jena/blob/master/jena-core/src/main/java/org/apache/jena/reasoner/rulesys/builtins/Difference.java#L68<https://github.com/apache/jena/blob/master/jena-core/src/main/java/org/apache/jena/reasoner/rulesys/builtins/Difference.java#L68><https://github.com/apache/jena/blob/master/jena-core/src/main/java/org/apache/jena/reasoner/rulesys/builtins/Difference.java#L68<https://github.com/apache/jena/blob/master/jena-core/src/main/java/org/apache/jena/reasoner/rulesys/builtins/Difference.java#L68>>
[2]
https://jena.apache.org/documentation/inference/#builtins<https://jena.apache.org/documentation/inference/#builtins><https://jena.apache.org/documentation/inference/#builtins<https://jena.apache.org/documentation/inference/#builtins>>
Could people recommend a good reference/tutorial on how to use built-ins
(greaterThan, difference, now etc) with dates (e.g., datetime, duration and so
on) in rules for the GenericRuleReasoner?
Example:
Assume a KB of conferences with their deadlines as xsd:dateTime.
Here are examples of SPARQL queries to find conferences whose deadlines are
passed:
SELECT * WHERE {
?subject here:hasDeadline ?date .
BIND((xsd:dateTime(?date) - now()) AS ?Span)
FILTER(?Span < "P0D"^^xsd:duration)
}
SELECT * WHERE {
?subject here:hasDeadline ?date .
FILTER(now() > xsd:dateTime(?date))
}
Suppose instead I wanted to infer some attribute of the conference, e.g:
?subject here:hasStatus here:DeadlinePassed
I don't really get how to do that in a rule and I can't quite figure if I'm
misusing the built-ins or just mixing SPARQL and rule syntax (e.g., when trying
to coerce variables to datatypes).
There's a bunch of recurring questions around that sort of rules but I can't
quite find any answer that's giving clear examples.
Thus I would find it useful if anybody could point at a resource that goes
through some sort of how to do date comparison and use that in rules as the
Jena doc on built-in is not self-contained in that respect.
https://jena.apache.org/documentation/inference/#rules<https://jena.apache.org/documentation/inference/#rules><https://jena.apache.org/documentation/inference/#rules<https://jena.apache.org/documentation/inference/#rules>>
With many thanks and kind regards,
Pierre
--
Lorenz Bühmann
AKSW group, University of Leipzig
Group: http://aksw.org<http://aksw.org><http://aksw.org<http://aksw.org>> -
semantic web research center
THIS E-MAIL MAY CONTAIN CONFIDENTIAL AND/OR PRIVILEGED INFORMATION.
IF YOU ARE NOT THE INTENDED RECIPIENT (OR HAVE RECEIVED THIS E-MAIL
IN ERROR) PLEASE NOTIFY THE SENDER IMMEDIATELY AND DESTROY THIS
E-MAIL. ANY UNAUTHORISED COPYING, DISCLOSURE OR DISTRIBUTION OF THE
MATERIAL IN THIS E-MAIL IS STRICTLY FORBIDDEN.
IN ACCORDANCE WITH MIFID II RULES ON INDUCEMENTS, THE FIRM'S EMPLOYEES
MAY ATTEND CORPORATE ACCESS EVENTS (DEFINED IN THE FCA HANDBOOK AS
"THE SERVICE OF ARRANGING OR BRINGING ABOUT CONTACT BETWEEN AN INVESTMENT
MANAGER AND AN ISSUER OR POTENTIAL ISSUER"). DURING SUCH MEETINGS, THE
FIRM'S EMPLOYEES MAY ON NO ACCOUNT BE IN RECEIPT OF INSIDE INFORMATION
(AS DESCRIBED IN ARTICLE 7 OF THE MARKET ABUSE REGULATION (EU) NO 596/2014).
(https://www.handbook.fca.org.uk/handbook/glossary/G3532m.html<https://www.handbook.fca.org.uk/handbook/glossary/G3532m.html>)
COMPANIES WHO DISCLOSE INSIDE INFORMATION ARE IN BREACH OF REGULATION
AND MUST IMMEDIATELY AND CLEARLY NOTIFY ALL ATTENDEES. FOR INFORMATION
ON THE FIRM'S POLICY IN RELATION TO ITS PARTICIPATION IN MARKET SOUNDINGS,
PLEASE SEE
https://www.horizon-asset.co.uk/market-soundings/<https://www.horizon-asset.co.uk/market-soundings/>.
HORIZON ASSET LLP IS AUTHORISED AND REGULATED
BY THE FINANCIAL CONDUCT AUTHORITY.
--
Lorenz Bühmann
AKSW group, University of Leipzig
Group: http://aksw.org<http://aksw.org> - semantic web research center
THIS E-MAIL MAY CONTAIN CONFIDENTIAL AND/OR PRIVILEGED INFORMATION.
IF YOU ARE NOT THE INTENDED RECIPIENT (OR HAVE RECEIVED THIS E-MAIL
IN ERROR) PLEASE NOTIFY THE SENDER IMMEDIATELY AND DESTROY THIS
E-MAIL. ANY UNAUTHORISED COPYING, DISCLOSURE OR DISTRIBUTION OF THE
MATERIAL IN THIS E-MAIL IS STRICTLY FORBIDDEN.
IN ACCORDANCE WITH MIFID II RULES ON INDUCEMENTS, THE FIRM'S EMPLOYEES
MAY ATTEND CORPORATE ACCESS EVENTS (DEFINED IN THE FCA HANDBOOK AS
"THE SERVICE OF ARRANGING OR BRINGING ABOUT CONTACT BETWEEN AN INVESTMENT
MANAGER AND AN ISSUER OR POTENTIAL ISSUER"). DURING SUCH MEETINGS, THE
FIRM'S EMPLOYEES MAY ON NO ACCOUNT BE IN RECEIPT OF INSIDE INFORMATION
(AS DESCRIBED IN ARTICLE 7 OF THE MARKET ABUSE REGULATION (EU) NO 596/2014).
(https://www.handbook.fca.org.uk/handbook/glossary/G3532m.html)
COMPANIES WHO DISCLOSE INSIDE INFORMATION ARE IN BREACH OF REGULATION
AND MUST IMMEDIATELY AND CLEARLY NOTIFY ALL ATTENDEES. FOR INFORMATION
ON THE FIRM'S POLICY IN RELATION TO ITS PARTICIPATION IN MARKET SOUNDINGS,
PLEASE SEE https://www.horizon-asset.co.uk/market-soundings/.
HORIZON ASSET LLP IS AUTHORISED AND REGULATED
BY THE FINANCIAL CONDUCT AUTHORITY.
