SWSL Rules Sketch of the proposed language

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SWSL RulesSketch of the proposed language

• BG MK

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Main Features

• Rule based with non-mon negation
• Literals
• Predicates
• Frames, class hierarchy, instances of classes,
  classes as instances (some OWL-Full features for
  cheap)
• Based on F-logic
• Higher-order syntax, first-order semantics
• Variables can be anywhere (predicate, function
  positions) which allows introspection of
  structure
• Reification rules, rule bodies, rule heads
• Based on HiLog

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Main Features (Contd)

• Rule priorities, constraints, negation in the
  rule head
• Does not add expressive power, but lets the
  programmer specify complex cases of negation much
  more succinctly and clearly
• Based on courteous LP approach by BG
• Useful for specifying complex policies etc.

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Main Features (Contd)

• Considering
• Procedural attachment
• State changing operators (a la SQL bulk updates)
• Triggers
• Based on Transaction Logic (and possibly some
  non-logical)

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Relationship to OWL

• Includes OWL Lite-
• See the paper by de Bruijn, Polleres, Fensel
  http//www.wsmo.org/2004/d20/v0.2/20040630/
• OWL Lite- includes the most significant features
  of OWL Lite
• Includes some of the features of OWL Full
• Classes as instances
• The exact intersection of SWSL Rules and OWL is
  not known at this time

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Example Travel Reservation

• Services can sell tickets from city A to city B
  or sell citipasses for a city.
• Features shown
• input as a reified object
• complex goals (Boolean combos)
• rules in postconditions and goals
• service effects can depend on input
• services/goals can include time ranges
• goals/services can contain universal quantifiers

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Example Taxonomy

• germany, france, europe, etc. classes of cities
• paris, bonn, etc. cities
• germany sub europe.
• austria sub europe.
• france sub europe.
• tyrol sub austria.
• Innsbruck in tyrol.
• lienz in tyrol.
• vienna in austria.
• bonn in germany.
• frankfurt in germany.
• paris in france.
• nancy in france.

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Example A Service Description

• Serv1 sells tickets citipasses
• serv1
• precondition(?Input) -
• ?Input
  like ?Reqfrom-?From and to-?To and
• ?Req in request and
  ?From in germany and ?To in austria
• or
• 
  ?Input like ?Reqcitipass- ?City and
• ?Req in request and ?City
  in tyrol
• and
• effect(?Input) -
• 
  (ticket(?Req)start-?From and destination-?To
  and timerange-12,18 -
• 
  ?Input like ?Reqfrom-?From and
  to-?To
• 
  and ?Req in request)
• and
• (pass(?Req)location-?City -
• 
  ?Input like ?Reqcitipass-?City
  ,

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Example A Goal

• Find services that can sell a pass for some city
  in Tyrol and for every city in France
• goal123
• input - _1citipass- ?_ and
• intent- ?Passlocation-?X in france or
  location-?X in tyrol
• and
• forall ?City (if ?City in
  france then
• 
  exists ?Pass1 (?Pass1location-?City) )
• and
• _1 in request.

Auto-generated new object Id
Issue Is adding quantifiers a good idea?
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A Service Discovery Rule

• doFindService(?Goal) -
• ?Goalinput - ?Input and
• ?Servprecondition(?Input) - ?Precond and
• ?Precond and
• ?Goalinput - ?FreshInput and
• ?Servpostcondition(?FreshInput) - ?PostCond
  and
• insertrule?PostCond and //
  hypothetically assume postcondition
• // Check if our goal is satisfied by the service
• ?Goalintent - ?Intent and
• if ?Intent
• then (write('Service ') and write(?Serv)
  and writeln(' matches!')) and
• // Remove the hypothetically added facts and
  rules
• deleterule?PostCond.

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Thoughts on a Bridge to SWSL Process

• serv1
• precondition(?Input) -
• and
• effect(?Input) -
• and
• processModel - (sand seq paint) par heat
  

Process model reified as a term
Process model could be a PSL statement or
expressed in some other language. We assume it
is some kind of a first-order statement.
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Thoughts on a Bridge (contd)

• goal123
• input -
• and
• intent -
• and
• processQuery - sand seq paint

Process query reified as a term
Matching of process query against process model
can be done using a first order theorem prover,
which can be treated as a procedural attachment
that takes 2 reified formulas and tells whether
one implies the other.