Re: Enhancing object-oriented programming with OWL

Timothy,

I understand you want to get the object model to work as close to OWL
as possible? But what is your motivation?

If it is to make systems more flexible and generic by enabling OWL
features in them, you might get better results by discarding the
domain object level altogether. I don't think this issue can be solved
by trying to fix model mismatches since abstractions are leaky (I dare
to say ORMs have not succeeded). The need for such complex development
as compiler reengineering is a good indication of this.

What is simple and works is keeping as close as possible to the single
pivotal model we currently have -- RDF/OWL, and its API such as Jena.

Martynas
graphity.org

On Mon, Aug 20, 2012 at 6:39 PM, Timothy Armstrong
<tim.armstrong@gmx.com> wrote:
> Hi,
>
> Well, if there would be some way to do multiple inheritance in Java, that
> could be very useful.  I was thinking it would probably be possible to do
> some of the class reasoning in Java with its limited support for multiple
> inheritance with interfaces, just we would be partially limited in what we
> can do with classes in Java.  There shouldn't be a problem with the property
> reasoning, SPARQL, or rules in Java though (well I have methods to compute
> all the triplestore indexes).  Semantic Web Services written as Java
> annotations on methods should work if annotations are extended to support
> arbitrary datatypes.
>
> I could have written the code in a language that has multiple inheritance,
> but we can do a lot in Java, and Java is just my best language.  It might be
> straightforward to copy the code to any other object-oriented language.  I
> just looked at Python decorators this morning, since Python has
> multiple-inheritance.  It doesn't look straightforward to use them just for
> metadata on code elements like Java annotations, but maybe it can be done.
> If it can, it looks like they would support arbitrary datatypes.  And then
> maybe we could add all of OWL, SPARQL, rules, and Semantic Web Services to
> Python without modifying Python...  Well, there would need to be something
> like AspectJ for Python as I'm doing it.
>
> Truthfully, I haven't spent much thought about how best to do the class
> reasoning.  I focused on the property reasoning and indexes and was waiting
> to talk to people about the class reasoning.  I'll have to look into the
> technologies you mention.
>
> Tim
>
>
>
> On 08/18/2012 04:55 PM, adasal wrote:
>>
>> We would need to modify a compiler to determine to which classes an object
>> belongs so we would know what methods can be used with it.  There could be
>> methods in defined classes.
>
>
> You must be thinking about a multiple class inheritance hierarchy.
>
> There is this project
> http://insightfullogic.com/blog/2011/sep/16/multiple-inheritance/
> but I think there must be other implementations.
> Further containers for IoC such as Tapestry have a mature mixin
> implementation for class transformation, or Scala (and Java 8 to be)
> supports traits.
> Wouldn't this cover it instead of messing around with the compiler?
>
> I would have thought the real problem is how to define precedence in the
> multiple hierarchy. How does OWL deal with contradictory definitions in the
> hierarchy?
>
> Adam
>
> On 18 August 2012 16:10, Timothy Armstrong <tim.armstrong@gmx.com> wrote:
>>
>> Hi Adam,
>>
>> What I have in mind is fitting my software together with Sesame or Jena
>> and just having the back-end store sets of objects instead of whole triples
>> and see how that works.  For benchmarks, I think it won't be very difficult
>> to get SPARQL running on my software, since I have methods to compute all
>> the triplestore indexes (permutations of subject-predicate-object) from all
>> of main memory, but SPARQL isn't running yet.
>>
>> I just meant that my understanding was that OWL can express anything about
>> data OOP can express, and more, but I'm sure Alan is right that there is
>> more than abstract classes. By "disparity" I meant that even if there are
>> differences between OOP and OWL of which I'm not aware, I still don't see a
>> problem with adding OWL to OOP.
>>
>> We would need to modify a compiler to determine to which classes an object
>> belongs so we would know what methods can be used with it.  There could be
>> methods in defined classes.
>>
>> Tim
>>
>>
>>
>> On 08/18/2012 07:35 AM, adasal wrote:
>>
>>
>>
>> On 17 August 2012 23:08, Timothy Armstrong <tim.armstrong@gmx.com> wrote:
>>>
>>> Certainly, object-oriented classes and OWL classes are different, but my
>>> understanding is that the main difference is just that OWL is strictly
>>> better.
>>
>>
>> What do you mean by 'strictly', 'better' and 'strictly better'?
>>
>>>
>>>  I'm not aware of anything OOP can do that OWL cannot do, but OWL can do
>>> a lot more.
>>
>>
>> What do you mean by 'do'? Do you mean it is more expressive such that it
>> is possible to define in OWL what cannot be defined in OOP? Isn't that
>> axiomatic in that they are different languages with different semantics?
>> What you are really saying is that you want to extend the syntax of OOP in
>> a form you think is convenient to use such that it will be able to express
>> OWL semantics.
>>
>>> Well, abstract classes, but that's all I can think of.
>>
>> So is this relevant?
>>
>>> Or if there is still going to be a disparity,
>>
>> What does this mean?
>>
>>>
>>> we should still just be able to add all the OWL class constructs and
>>> everything else about OWL and let people use them in OOP.
>>
>> You mean with your annotations - but the issue really is whether this is
>> more convenient than existing approaches.
>>
>>>
>>> We'd need to get into a compiler to do some of it, but I think it would
>>> be worth it.
>>
>> Why would it be necessary to get into the compiler, what are you talking
>> about?
>> Do you mean to pick up annotations - that is not necessary as new
>> annotations can be defined as things stand - or to optimise such as in the
>> way you mention where reasoning is selective. I can't see that this needs
>> access to the compiler so much as an understanding of the logic of whether
>> and when selective reasoning is a proper optimisation.
>>
>> You would have to show that your approach is better than the existing
>> approaches to optimisation that sit on top of triple and quad stores.
>> Can you do this?
>>
>> Adam
>>
>>
>
>

Received on Monday, 20 August 2012 21:51:34 UTC