1. www.ontoprise.de © 2005 ontoprise GmbH Home - 1 - | Menu | Partner | End Copyright ©2005 ontoprise GmbH, Karlsruhe F-Logic Forum: Results and Open Issues left Martin Weindel, 28-10-2006 www.ontoprise.de

2. © 2005 ontoprise GmbH Home - 2 - | Menu | Partner | End Agenda  New F-Logic Specification, why?  Highlights of New F-Logic  Parser for New F-Logic  Open Issues

3. www.ontoprise.de © 2005 ontoprise GmbH Home - 3 - | 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

4. www.ontoprise.de © 2005 ontoprise GmbH Home - 4 - | Menu | Partner | End Highlights Highlights of New F-Logic

5. www.ontoprise.de © 2005 ontoprise GmbH Home - 5 - | 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="http://purl.org/dc/elements/1.1/".  Modules to isolate different parts of KB, only one module per file :- _module _"http://foo.org/onto#m2".  More directives: _version, _encoding,...

6. www.ontoprise.de © 2005 ontoprise GmbH Home - 6 - | Menu | Partner | End Directives Example  Without directives _"http://foo.org/onto#Doc3"[ _"http://purl.org/dc/elements/1.1/creator" -> "Billy Smith", _"http://purl.org/dc/elements/1.1/subject" -> "Improved Readability"]@_"http://foo.org/onto#m2".  With directives :- _module _"http://foo.org/onto#m2". :- _default prefix = "http://foo.org/onto#". :- _prefix dc="http://purl.org/dc/elements/1.1/". #Doc3[dc#creator -> "Billy Smith", dc#subject -> "Improved Readibility"]. No explicit module needed Default prefix

7. www.ontoprise.de © 2005 ontoprise GmbH Home - 7 - | 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).

8. www.ontoprise.de © 2005 ontoprise GmbH Home - 8 - | 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.

9. www.ontoprise.de © 2005 ontoprise GmbH Home - 9 - | 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[son@(Woman) =>> Man]. Adam:Man[son@(Alibama) - >> {Jaus,Jalomus,Coreus}; son@(Ada) ->> Aliphaz].

10. www.ontoprise.de © 2005 ontoprise GmbH Home - 10 - | 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}}.

11. www.ontoprise.de © 2005 ontoprise GmbH Home - 11 - | Menu | Partner | End Parser A Parser for the new F-Logic

12. www.ontoprise.de © 2005 ontoprise GmbH Home - 12 - | 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

13. www.ontoprise.de © 2005 ontoprise GmbH Home - 13 - | Menu | Partner | End Parser: Technical Details  Implemented in Java using parser generator ANTLR 3.0 (see http://www.antlr.org ) http://www.antlr.org  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

14. www.ontoprise.de © 2005 ontoprise GmbH Home - 14 - | 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

15. www.ontoprise.de © 2005 ontoprise GmbH Home - 15 - | Menu | Partner | End Demo  Parser demonstration at http://217.110.222.146:12080/ demoparser/ForumFlogicParser.html

16. www.ontoprise.de © 2005 ontoprise GmbH Home - 16 - | 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?)

17. www.ontoprise.de © 2005 ontoprise GmbH Home - 17 - | Menu | Partner | End Open Issues

18. www.ontoprise.de © 2005 ontoprise GmbH Home - 18 - | 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) _"http://bmw/z4" => URI ( = 'http://bmw/z4' ???)  Inconsistent notation for symbols with prefix: String + Symbol = URI :- _prefix a = "http://foo/". a#'bar' == _"http://foo/bar"

19. www.ontoprise.de © 2005 ontoprise GmbH Home - 19 - | 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 ?- "http://foo/"#?X  Query for namespaces for given local name ?- ?X#bar  Is # an operator? If yes, then strings should be allowed before # ?- 'http://foo/bar'[att -> ?X]. ?- "http://foo/"#bar[att -> ?X].

20. www.ontoprise.de © 2005 ontoprise GmbH Home - 20 - | 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 q(?X)@?M :- p(?X)@?M.

21. www.ontoprise.de © 2005 ontoprise GmbH Home - 21 - | 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

22. www.ontoprise.de © 2005 ontoprise GmbH Home - 22 - | 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

23. www.ontoprise.de © 2005 ontoprise GmbH Home - 23 - | Menu | Partner | End Open Source Reference Parser  Next Steps:  Refine this parser to become the reference parser  Release as Open Source