Re: [RIFRAF] ACTION 173: Initial Ontology for Action Language Discriminators

Leora Morgenstern wrote:
> 
> 
> public-rif-wg-request@w3.org wrote on 04/25/2007 04:24:57 AM:
> 
>  >
>  > Leora Morgenstern wrote:
>  > >
>  > > Attached please find the initial pass at an ontology for action
>  > > languages (Action 173).  
>  > >
>  > >
>  > > Some remarks on the ontology.
>  > >
>  > > 1.I built my ontology on top of the ontology that Allen Ginsberg had
>  > > created for Action 173 (ontologizing semantic discriminators). This
>  > > approach has the advantage of dealing with at least some integration
>  > > issues from the start, instead of deferring them to a later date.
>  > >
>  > > 2. As discussed during earlier telecons, I broadened the original
>  > > mandate for this action, which was to create an ontology for
>  > > discriminators for  ECA (event-condition-action) rules, which are used
>  > > mainly to describe updates to databases. I looked at the more general
>  > > problem of discriminators for AI action languages.
>  > > These more general action languages would seem to be needed to 
> represent
>  > > the use cases in the UCR document. (For example, in the use case 
> Ruleset
>  > > Integration for Medical Decision Support, one reasons about various
>  > > medical events, such as Bob’s Hb1AC levels increasing, the 
> doctor
>  > > prescribing various medications, Bob’s reactions to them, 
> and Bob’s
>  > > taking a medical test.) ECA rules, which are much narrower in 
> scope, can
>  > > be considered a subset of general action rules.
>  > >
>  > > Examples of such general AI action languages include the situation
>  > > calculus, the event calculus, the fluent calculus, temporal action
>  > > logics, and  the action description languages \cal{A}, and \cal{C}
>  > >
>  > > 3. These languages share certain features, but differ on other 
> features.
>  > > A list of features of interest follows:
>  > >    
>  > > a. Division into sets of sentences: domain description, observation
>  > > sentences, queries. /(It is almost universally accepted to have at the
>  > > first two classes of sentences in action languages.)/
>  > > b. Intervals vs. time points. vs. both /(E.g., the event calculus has
>  > > both time points and intervals; sitcalc has situations/time points,
>  > > \cal{A} has time points.)/
>  > > c. Discrete time vs. continuous time /(Situation calculus: discrete
>  > > time; fluent calculus,  event calculus: continuous time)/
>  > > d. Branching time vs. linear time; branching forward only vs. 
> branching
>  > > both forward and backward /(Event calculus: linear time; situation
>  > > calculus: forward branching time.)/
>  > > e. Causation as an explicit relation vs. concept explicit in rule 
> and/or
>  > > material implication. /(Explicit in \cal{C}; implicit in temporal 
> action
>  > > logics, EC, SC.)/
>  > > f. Causal rules; state constraints
>  > > g. Concurrency: concurrency disallowed; concurrent processes allowed,
>  > > but can’t have them starting at exactly the same time
>  > > (asynchronicity).  /(Fluent calculus, event calculus: concurrency
>  > > allowed; vanilla sitcalc; only one action at a time; extended
>  > > (Reiter-style) situation calculus: asynchronicity.)/
>  > > h. Explicit agent vs. implicit agent
>  > > i. Single agent vs. multiple agent
>  > > j. Determinism vs. non-determinism
>  > > k. Solving the frame problem: monotonic solutions (explanation closure
>  > > axioms; Reiter) vs. nonmonotonic solutions (using circumscription, or
>  > > answer-set semantics, e.g. together with an appropriate formulation of
>  > > the commonsense law of inertia)
>  >
>  > Note that a further distinction in the action languages you mention, is
>  > that interia is not always implicit.
> 
> Could you let me know what "interia" is? I googled, but that didn't help.

basically frame axioms, ie that atoms (also called fluents in these 
languages) keep there value if not affected by any action over a state 
change. Intertia can be defined "per fluent" in some of these languages...

>  >As far as I remember, it is in
>  > \cal{A}, but not in \cal{C} (or the related language \cal{K} which we
>  > developed in Vienna during my thesis...)
>  >
>  > In that context, it would maybe also, even be worthwhile to look into
>  > planning languages like PDDL.
>  >   The PDDL work might by itself be interesting, since it is also kind of
>  > a family of languages around a common core, where features can be
>  > added/left out, maybe providing some inspiration for the extension
>  > mechanism for dialects...
>  >
>  > Axel
> 
> Axel, I think it would be very interesting to look at PDDL --- I agree 
> that the way
> it has been developed, over time, from a common core, could be a model
> for how we develop methods for RIF's handling of different dialects 
> (down the road).
> 
> I will also look at \cal{K} --- thanks for the reference!
> 
> In the meantime, however, as Chris and Sandro pointed out yesterday, I need
> to refocus this work on RIF's short-term goals and the RIF Core. This means
> less focus, at least in the short term, on many of the distinctions that
> I've thus far put in the ontology, which are model-based and/or based on
> the method of inference.

fair enough.

best,
axel

> Nevertheless, I agree with you that it's important for us, as we continue
> in this work, to be aware of as many of the languages, systems, and 
> issues that are out
> there, as possible.
> 
>  >
>  > > l. All actions have preconditions and effects. Can also have failure
>  > > conditions and success conditions. (Success conditions different than
>  > > preconditions.)
>  > >
>  > > 4. The different features are sometime superficial, but may reflect
>  > > different deep-seated foundational assumptions. Different sets of
>  > > assumptions underlying these languages could make translation 
> difficult.
>  > >  Of importance is the growing set of results on methods of 
> translations
>  > > between various pairs of languages (e.g., between TAL and   sitcalc,
>  > > fluent calc and various formalisms).
>  > >
>  > > 5. The exercise of constructing the ontology brought to light some
>  > > interesting questions regarding the categorization of these features.
>  > >  Does the distinction between single agents and multiple agents belong
>  > > to the model or the theory? What about the distinction between the
>  > > concurrency and asynchronicity? I’ve done a first effort at 
> addressing
>  > > these issues, but they remain open for discussion.
>  > >
>  > > Best regards,
>  > > Leora
>  >
>  >
>  > --
>  > Dr. Axel Polleres
>  > email: axel@polleres.net  url: http://www.polleres.net/

>  >
>  >
>  >
>  >


-- 
Dr. Axel Polleres
email: axel@polleres.net  url: http://www.polleres.net/

Received on Wednesday, 25 April 2007 13:39:14 UTC