IncorporatingCluster-BasedRelationshipsin Web Rule Language

Transcription

1 IcorporatigCluster-BasedRelatioshipsi Web Rule Laguage Mala Mehrotra Pragati Syergetic ResearchIc. Cupertio. CA 1 Itroductio The Sematic Web visio requires rule-based systems to express the kowledge ecessary for extractig ad utilizig distributed iformatio o the web. As the sematic web grows, it is importat that we facilitate the maiteace, reuse ad iteroperability of axioms by allowig higher-level kowledge about them to be expressed via more expressive rules. I the course of aalyzig a wide variety of kowledge-based systems, Pragati has foud may types of cluster-based relatioships that ca eable aalysts ad developers to comprehed, maitai, ad reuse such systems more effectively. Pragati s cluster-based aalysis of umerous kowledge-based systems through its Multi-ViewPoit Clusterig Aalysis (MVP-CA) Tool [Mehrotra & Bobrovikoff 2002] has demostrated that clusterig ca expose a wide variety of relatioships betwee formally represeted cocepts. These iclude templatizatio ad refactorig opportuities, expositio of idioms, such as iverse rules, idempotet rules, ad potetial iter-system mappigs. Pragati s existig tool suite provides statistics- ad heuristics-based clusterig o axioms i kowledge bases that eables sophisticated aalytical capabilities o the properties of the clusters of axioms. Higher-level relatioships based o the clusters have bee the domai of huma aalysts, ad have bee geerally expressed as writte reports ad had-geerated diagrams. It is our positio that ay rule laguage for the sematic web should have the expressivity ad the extesibility to represet diverse metadata to ecapsulate such fidigs. This positio paper presets some represetative results from Pragati s high-level clusterig aalysis that eeds to be expressed i the W3C rules beig desiged for iteroperability, reuse ad maiteace. 2 Represetig Cluster-Based Aalysis Results Pragati s techology cosists of a itegrated suite of cluster-based cogitive assistace tools based aroud Pragati s core capability of automatically groupig cocepts through the MVP-CA tool. It facilitates aalysis of rule based systems by clusterig the rules ito clusters that share sigificat commo properties. It exposes rule-based system developers to the usage of the rules 1

2 by clusterig the iformatio uits that exercise/use the system i a give practical cotext. I its curret state, MVP-CA tool ca accept may differet types of kowledge bases or decisio support systems ad expose coceptual islads or clusters of cocepts i the viciity of a seed cocept. These viciity cocepts aid the user s comprehesio of kowledge bases ad lead to fortuitous reuse opportuities eve whe the source kowledge bases are ufamiliar to the user [Hayes et.al 2005]. I this sectio we will preset some represetative examples of issues Figure 1: Sapshot of the MVP-CA Tool Template formed from JPL s SWEET Earthrealm OWL Otology. 2

3 foud through the MVP-CA tool which ca help ifluece the desig of the web laguage of future. 2.1 Templatizatio of Usage Patters Clusters of structurally similar axioms sigal prototypical usage patters for cocept(s). Idetificatio of such regios i the software ca be a valuable guide for future extesios of the kowledge base, as well as provide us opportuities for idetifyig geeric, reusable regios i the software [Mehrotra et.al 1999]. Exposig commo fuctioalities, as well as overlappig cotexts across clusters of axioms, reveals opportuities for creatio of higher order predicates for axioms, such as macro predicates i Cyc, ad templates for groups of axioms [Mehrotra 2002]. Ofte the eed for these higher-level abstractios ca be revealed oly ex post facto, that is, after there are eough assertios i the kowledge base to warrat the formatio of a higher order axiom. These importat kowledge represetatioal issues ca impact the log-term utility ad quality assurace of the kowledge base. I Figure 1, we preset a sapshot of the templatig ifrastructure from the MVP-CA tool showig a represetative cluster from JPL s SWEET Earthrealm kowledge base writte i OWL DL. The template is formed automatically i the overlaid widow by performig rule differecig operatio o a selected rule set. The cluster selected i Figure 1 shows how differet types of scalar operatios, such as, ScalarSummatio, ScalarSubtractio, ScalarMultiplicatio ad ScalarDivisio are defied OWL-DL by placig similar value restrictios o the class ScalarOrVariableOrOperatio, ad similar property restrictios o hasfirstoperad ad hassecodoperad. These templates ca be flagged ad documeted i the curret MVP-CA ifrastructure. I our experiece with various types of kowledge bases, opportuities for template formatio arise repeatedly, regardless of the domai or the represetatio laguage. Capturig these templates i a succict rule-represetatio laguage will allow them to become easily available for search, retrieval ad reuse across kowledge bases i the larger cotext of the sematic web. 2.2 Refactorig I may cases, we have foud portios of kowledge-based systems that could beefit from various types of refactorig. Figure 2 shows a depedecy diagram view of two clusters ad the mostly-overlappig term sets that they use. The domai rules i this case are from the IMMACCS (Itegrated Marie Multi-Aget Commad ad Cotrol System) Clips system ad they represet the various situatios whe the object betwee the weapo ad target trajectory could be a rotary wig or a blockig buildig. I this case, the rules i the clusters are parallel, ad it would be useful to refactor both the rules ad the otological defiitios they use [Mehrotra & Bobrovikoff 2001]. 3

4 WeapoSelectio TrackPositio Platform LethalWeapo Positio Muitio s Age t Etit y CallFor Fire Dimesio Rotary Wig Structure Cluster: coflict due to blockig rotary wig Rules: Structure_Trajectory_Weapo Structure_Trajectory_Etity Structure_Trajectory_Platform Cluster: coflict due to blockig buildig Rules: RotaryWig_Trajectory_Weapo RotaryWig_Trajectory_Etity RotaryWig_Trajectory_Platform Figure 2: Refactorig the cocept of coflicts from IMMACCS Fires aget However, while it is possible to model refactorig at several differet levels of detail, a good startig poit would be to describe the startig set of etities ad the edig (i.e., trasformed) (#$implies (#$ad (#$subsituatiotypes?coa?task) (#$icreasessittype-g (#$evaluatesdimesioofcoa?coa #$mitigateriskfactorsi set of etities. At this level, it would be ecessary to represet the etities first as commo 4

5 subregios i a rule-laguage ad have trasformatios o those rules to achieve the refactorig effect. 2.3 Iverse Cocepts I the third example, show i Figure 3, we see that there are two legitimate ways of expressig the mitigateriskfactorsicoa ad Effective/IeffectiveForPurpose. O close aalysis these Cyc [Cycorp] axioms ca be recogized as ear iverses of each other [Pool et.al 2003]. The user ca create a associatio betwee the rule etities ad label the associatio ear iverse of. Future queries that tur up either oe of the rules should also tur up the compaio opposite rule so that the authors are aware of the various legitimate represetatios. This requires us to defie a iverse rule costruct i the web rule laguage just as we have for iverse cocepts. 3 Bibliography CYCORP P. Hayes, T. Eskridge, M. Mehrotra, D. Bobrovikoff, T. Reichherzer, R. Saavedra. (2005) COE: Tools for Otology Developmet ad Reuse. Submitted to 2005 Iteratioal Coferece o Itelligece Aalysis, May 3-5, 2005, McLea, VA. M. Mehrotra. (2004) Sematic Mediatio Tools for Iteroperability. 6th Aual ONR Workshop o Collaborative Decisio Support Systems. Sept 8-9, Quatico, VA. pp: M. Pool, K. Murray, J. Fitzgerald, M. Mehrotra, R. Schrag, J. Blythe, J. Kim, H. Chalupsky, P. Miraglia, T. Russ, & D. Scheider. (2003} Evaluatig SME-Authored COA Critiquig Kowledge. K-CAP 2003, October 23-25, Saibel Islad, Florida. Mehrotra M.. (2002) Otology aalysis for the Sematic Web. Otologies ad the Sematic Web: Papers from the AAAI Workshop (Techical Report WS-02-11). Edmoto, Caada: AAAI Press. Mehrotra, M., & Bobrovikoff, D. (2002). Multi-viewpoit clusterig aalysis tool. Proceedigs of the Eighteeth AAAI Coferece (pp ).Edmoto, Caada: AAAI Press. Mehrotra M., & Bobrovikoff, D. (2001). Multi-Viewpoit Clusterig Aalysis (MVP-CA) Techology for Aalysis of the Itegrated Marie Multi-aget Commad ad Cotrol System (IMMACCS). Proceedigs of ONR Decisio-Support Workshop o Cotiuig the Revolutio i Military Affairs. Jue 2001, Quatico, VA, CDM Techologies, Sa Luis Obispo, CA. 5

6 Mehrotra et al. (1999) M. Mehrotra, S. Alvarado ad R. Waiwright. Layig a Foudatio for Software Egieerig of Kowledge Bases i Spacecraft Groud Systems. Proceedigs of FLAIRS99 Coferece. Special Track o AI Applied to Spacecraft Autoomy, Florida. Mehrotra M. ad Wild C. (1995) Aalyzig Kowledge-Based Systems usig Multi- Viewpoit Clusterig Aalysis. Joural of Systems ad Software, 29: ,