Ontolog Forum

Session Track C Session 1
Duration 2 hour
Date/Time Mar 22 2017 16:30 GMT
9:30am PDT/12:30pm EDT
4:30pm GMT/5:30pm CET
Convener DonnaFritzsche and RamSriram

Ontology Summit 2017 Track C Session 1

Note that in the US Daylight Savings Time is in effect but Europe is still on standard time

Ontologies and Reasoning

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[12:29] Donna Fritzsche: welcome everyone!

[12:33] Donna Fritzsche: Ram will speak first and the Eugen

[12:34] Donna Fritzsche: followed by Pascal and Jans

[12:39] FrankOlken: Any prospect of moving these sessions a little earlier, e.g. 9:00am pdt?

[12:40] Donna Fritzsche: Hi Frank,

[12:41] Donna Fritzsche: We moved to Wed. to better accommodate some schedules. We can reconsider next year.

[12:42] KenBaclawski: @FrankOlken: The Summit Organizing Committee discussed this at length and also sought community feedback. We specifically considered 9:00am versus 9:30am PDT and the consensus was to stay at 9:30am PDT. We can reconsider days and times next year.

[12:48] AndreaWesterinen: Will the slides be available?

[12:49] Donna Fritzsche: yes, we asking that they be sent afterwards

[12:49] Pascal Hitzler: I'll make my slides available after the talk. I've already sent mine to Ken.

[12:49] gary berg-cross: @FrankOlken we actually tried some Summit organizing sessions at 9:00am PDT and it didn't attract any better attendance.

[12:50] Pascal Hitzler: I can post a temporary (dropbox) link if it helps during the presentation.

[12:51] AlexShkotin: no slides on BJN for me:-(

[12:51] KenBaclawski: The slides are now on the meeting page. See

[12:52] Pascal Hitzler: thanks, Ken

[12:53] KenBaclawski: @AndreaWesterinen: Eugen's slides are at

[12:54] KenBaclawski: @AndreaWesterinen: Pascal's slides are at

[12:59] AndreaWesterinen: @Ken Thanks. I got them from the updated web page.

[13:16] Donna Fritzsche: question for Eugen - how does the selection process/axiom narrowing relate (if at all) to the Rete Algorithm

[13:19] Donna Fritzsche: welcome Jans!

[13:32] Eugen Kuksa: Donna: I haven't heard of the Rete algorithm before, but as far as I can see from a quick overview, the selection process does not relate to it. In our premise selection, we use the ontology's analysis result (parsed axioms/conjectures and symbols) to pick some axioms and then write them back into a file (unchanged except for whitespace) along with the conjecture. The prover is then supplied this file.

[13:33] MarkUnderwood: I guess Rete is too 80's :)

[13:40] Jans Aasman: Hi: I can't start the blue jeans app, it basically totally kills my laptop

[13:40] Jans Aasman: I'm listening via the phone and I could present via my colleagues laptop

[13:43] Ram D. Sriram: Jans: Can you email us Ken the slides?

[13:45] Jans Aasman: I already did that ... can you check?

[13:46] Ram D. Sriram: Got it. I will ask Ken to take care of it.

[13:48] AndreaWesterinen: @Pascal Why wouldn't you use SPARQL Update to remove a conflicting axiom when new knowledge is added?

[13:49] MarkUnderwood: Would be interested in forwarding your comments to W3C if you have a position statement . . . or perhaps this is on our listserv?

[13:50] Ram D. Sriram: @Mark: Rete-based tools are still powerful.

[13:54] Pascal Hitzler: @Andrea - there are several issues with this. One is that you would have to know which axiom to remove - if the conflict comes out of a reasoning process, then it is usually a set of axioms which jointly produce the conflict. Which axiom do you want to remove then? Of course, in the particular example I gave, you'd only want to remove the moreBiodiverseThan relations, so your suggestion would be a work-around. But at the same time, it seems conceptually awkward, a "hack", to deal with it that way.

[13:55] Pascal Hitzler: @Mark were you refering to the SHACL comments?

[13:55] Pascal Hitzler: Ah no, it was part of the Rete discussion (forget my comment).

[13:56] Pascal Hitzler: I have to sign off at 2pm, feel free to contact me by email if there are any further questions.

[13:56] MarkUnderwood: @Pascal, ack'd. but would like to provide W3C feedback if you have not already done so.

[13:56] AndreaWesterinen: @Pascal I have been able to work around some of these issues by using named graphs to store the reasoning results (or perhaps different beliefs of different people/groups), and then analyzing the differences between the reasoning results.

[13:57] AndreaWesterinen: @Ken The link to Jan's slides (on the call page) result in an access denied.

[13:58] Pascal Hitzler: @Andrea: yes that's a way how to do it while using current standards. So from that perspective it's a "practical" solution. As a researcher, though, I'd be happier if a more principled solution could be developed (and at some stage be standardized).

[13:59] KenBaclawski: @[13:32] Eugen Kuksa: One can easily constrain a Rete network to include only a subset of the rules. In fact, it is a normal practice to prioritize rules.

[14:00] KenBaclawski: @AndreaWesterinen: Jan's slides will be publicly released after the meeting.

[14:01] AndreaWesterinen: @Pascal Given current tools and simplicity of the solution, I have found this approach valuable but would be happy for a "more principled" solution - as long as it is still simple. :-)

[14:01] FabianNeuhaus: @Ken: Do you have a reference about constraining a Rete network in the way you describe?

[14:02] Pascal Hitzler: @Andrea - no objections here :)

[14:06] FabianNeuhaus: @Donna: the axiom selection algorithm that Eugen presented is very different from Rete. The Rete algorithm is basically just an efficient way of executing simple rules and, thus, forward chaining. Eugens algorithm works on any monotonic logic (including higher-order logic) and it works backwards from the conjecture.

[14:24] gary berg-cross: Have to head off to an in town meeting. Will work on Track A synthesis in prep for next week's session.

[14:29] Donna Fritzsche: thankyou Fabian

[14:31] Donna Fritzsche: Thank-you to our speakers and audience.


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