© 2005 ontoprise GmbH Home | Menu | Partner | End Copyright ©2005 ontoprise GmbH, Karlsruhe F-Logic Forum: Results and Open Issues left Martin Weindel,

© 2005 ontoprise GmbH Home | Menu | Partner | End Agenda  New F-Logic Specification, why?  Highlights of New F-Logic  Parser for New F-Logic  Open Issues

© 2005 ontoprise GmbH Home | Menu | Partner | End New F-Logic Specification, why?  Original paper on F-logic published 1995  Various systems based on F-logic: Flora-2, Ontobroker, Florid,...  Problem areas:  New ideas  incompatible syntax extensions  Differences in Semantics  Usability and syntax inconsistencies => Forum F-Logic to define new specification

© 2005 ontoprise GmbH Home | Menu | Partner | End Highlights Highlights of New F-Logic

© 2005 ontoprise GmbH Home | Menu | Partner | End Highlights I: Directives  Usage of directives on a per-file basis  Namespace Prefixes to simplify dealing with URIs, following the RDF construct (sQNames) :- _prefix dc="  Modules to isolate different parts of KB, only one module per file :- _module _"  More directives: _version, _encoding,...

© 2005 ontoprise GmbH Home | Menu | Partner | End Directives Example  Without directives _" _" -> "Billy Smith", _" -> "Improved  With directives :- _module _" :- _default prefix = " :- _prefix dc=" #Doc3[dc#creator -> "Billy Smith", dc#subject -> "Improved Readibility"]. No explicit module needed Default prefix

© 2005 ontoprise GmbH Home | Menu | Partner | End Highlights II: Variables  Variables are denoted as ?Var  Implicit quantification ?X[grandfather -> ?G] :- ?G = ?X.father.father. Old: forall X,G X[grandfather -> G] :- G = X.father.father.  Anonymous variables ? or ?_  Explicit quantification ( forall, exist ) still supported p(?X) :- q(?X, ?_) and exist ?Y r(?X, ?Y).

© 2005 ontoprise GmbH Home | Menu | Partner | End Highlights III: If-then-else  Support for if-then-else rules to improve readability of simple rules for laymen if ?X:Person.age >= 18 then ?X:Adult else if ?X.age >= 12 then ?X:Teenager else ?X:Child.

© 2005 ontoprise GmbH Home | Menu | Partner | End Highlights IV: Syntax changes  Various syntax changes, most important:  Set value attributes only, i.e. dropping double arrows operators ->>, =>>, *->>, *=>>,.., !!  Usage of comma, or and instead of semicolon to separate parts in Flogic-molecules  Hi-Log syntax for method arguments dropped) New Syntax Man[son(Woman) {0:*} => Man]. Adam:Man[son(Alibama) -> {Jaus,Jalomus,Coreus}, son(Ada) -> Aliphaz]. Old Syntax =>> Man]. - >> {Jaus,Jalomus,Coreus}; ->> Aliphaz].

© 2005 ontoprise GmbH Home | Menu | Partner | End Highlights V: Aggregate  Syntax for aggregates as proposed in FLORA-2 : ?Var = Aggregate {?Var [GroupingVarList] | Query} ?- ?Z = min {?S | john[salary(?Year)->?S]}. ?- ?Z = count{?Year | john.salary(?Year) ?S], ?Y < Year}}.

© 2005 ontoprise GmbH Home | Menu | Partner | End Parser A Parser for the new F-Logic

© 2005 ontoprise GmbH Home | Menu | Partner | End From Spec To Code  Parser implemented from scratch using 1. Specification web pages of Forum Flogic 2. Discussions and results in Forum Flogic mailing list 3. Some „gap filling“ with parts from  FLORA-2  Ontobroker

© 2005 ontoprise GmbH Home | Menu | Partner | End Parser: Technical Details  Implemented in Java using parser generator ANTLR 3.0 (see )  LL(*) parser => more powerful => more natural grammar  Error recovery  Code generation possible for other languages (needs rewrite of actions and model classes)  C++  C#  Python

© 2005 ontoprise GmbH Home | Menu | Partner | End Parser Workflow Lexer Parser Path Expression Expansion Flogic Text Internal Parse Tree with Path Expr. and F-Molecules Expanded Parse Tree only containing F-Atoms

© 2005 ontoprise GmbH Home | Menu | Partner | End Demo  Parser demonstration at demoparser/ForumFlogicParser.html

© 2005 ontoprise GmbH Home | Menu | Partner | End Unsupported Syntax Features  Reification  Introspection  Syntax for forcing evaluation of evaluable functions  File loading syntax  Meta unification (part of spec?)  User defined equality :=: (part of spec?)

© 2005 ontoprise GmbH Home | Menu | Partner | End Open Issues

© 2005 ontoprise GmbH Home | Menu | Partner | End Open Issue: Strings, Symbols, and URIs  Unification of Strings, symbols, URIs?  Difference between symbol and string not easy for normal users "BMW Z4" => String (double quote) 'BMW Z4' => Symbol (single quote) _" => URI ( = ' ???)  Inconsistent notation for symbols with prefix: String + Symbol = URI :- _prefix a = " a#'bar' == _"

© 2005 ontoprise GmbH Home | Menu | Partner | End Open Issue: Namespaces  RDF sQNames are not sufficient:  GUIs will show only local part => Heuristics needed to separate namespace  Query for all objects of a given namespace ?- "  Query for namespaces for given local name ?- ?X#bar  Is # an operator? If yes, then strings should be allowed before # ?- ' -> ?X]. ?- " -> ?X].

© 2005 ontoprise GmbH Home | Menu | Partner | End Open Issue: Modules in Rule Head  Spec suggests to disallow module specification in rule head to enforce encapsulation  But module specs in rule head are currently used in some cases:  Axioms  Modelling of processes  Predefined rule sets working on modules with similar structure :-

© 2005 ontoprise GmbH Home | Menu | Partner | End Open Issue: Embedded modules  Need to import concepts and attributes from upper ontology  Need to make instances visible to upper ontology rules Upper Ontology Domain Ontology 1 Domain Ontology 2 Inherits concepts & attributes

© 2005 ontoprise GmbH Home | Menu | Partner | End Other Open Issues  Rule & query syntax Only head :- body. Or is <- allowed alternatively?  Old style rules and queries starting with forall?  Ontobroker query extensions sortedby, orderedby?  Documentation of rules and queries?  Unicode escape sequences in strings and symbols?  Syntax for rule labels?  Allowed encoding specifications  Readability of BooleanMethod specifications? ... => Discussion in Forum mailing list

© 2005 ontoprise GmbH Home | Menu | Partner | End Open Source Reference Parser  Next Steps:  Refine this parser to become the reference parser  Release as Open Source