LG617 A brief introduction to XLE

1. LG617 A brief introduction to XLE Kakia Chatsiou achats@essex.ac.uk Dept of Language and Linguistics University of Essex LG617 - XLE Lab

2. Outline About XLE Where is XLE used? ParGram Project Project Objectives Participating Members Powerset XLE Web interface A closer look at XLE Grammar architecture Inspecting a basic grammar .lfg file XLE interface XLE vs LFG notations Hands-on Session  LG617 - XLE Lab

3. About XLE • XLE stands for Xerox LinguisticsEnvironment • Under current development at PARC (Palo Alto Research Center, USA) • A computational environment developed to facilitate the writing and debugging of Lexical Functional Grammars • C-structure, f-structure, s-structure, and further projections can be defined • Implemented in C; works in Unix, Linux, MacOS. • Integrates a morphological analyser employing Finite State Technology • Can be used for both parsingandgeneration • Includes tools for various grammar development activities (such as analysing performance, test-suites) LG617 - XLE Lab

4. Where is XLE used? • ParGram Project • The core technology used in the consumer search engine based on natural language processing which is currently under development by Powerset LG617 - XLE Lab

5. Where is XLE used? :: ParGram Project :: Project Objectives • Broad coverage grammars • Inclusion of important and frequently occurring constructions • Linguistically motivated analyses • Parallel and crosslinguistic development of grammars between the participating members • All grammars are guided by a common set of linguistic principles and a commonly agreed upon set of grammatical analyses and features • Identical treatment of core crosslinguistic phenomena • Methods in grammar engineering • Common test methods and evaluation strategies • Balance between efficiency, performance, reliability and maintainability across grammars LG617 - XLE Lab

6. Participating Members Where is XLE used? :: ParGram Project :: Essex Greek, Welsh Manchester Arabic Oxford Malagasy Bergen, Norway Georgian, Norwegian, Tigrinya DCU, Ireland Chinese, English, French, German, Japanese, Spanish Fuji XEROX Japanese Ho Chi Minch Vietnamese PARC, CA Chinese, English, French Debrecen Hungarian IMS, Stuttgart German Konstanz Urdu Sabanci, Istanbul Turkish LG617 - XLE Lab

7. Where is XLE used? :: Powerset Search Engine :: • a Silicon Valley Company, currently building a transformative consumer search engine based on natural language processing: • It is based on technologies that take advantage of the structure and nuances of natural language • It offers an innovative approach to searching: • It breaks the confines of keyword search  queries using both keywords, short phrases and natural language • Makes search more natural and intuitive • Aims at fundamentally changing how we search the web and at the same time delivering higher quality results • currently searching Wikipedia with the help of FreeBase as the semantic knowledge database (source: http://www.powerset.com ) LG617 - XLE Lab

8. Where is XLE used? :: Powerset Search Engine :: LG617 - XLE Lab

9. Where is XLE used? :: The XLE Web Interface :: • a web-based tool for parsing LFG grammars using the XLE tool • outputs c-structures, f-structures and mrs-structures. • allows the user to choose a grammar and type in a sentence to be analyzed. The sentence is then processed by the XLE parser, and the resulting structures are displayed. • has a facility for uploading (small) user grammars, mainly for teaching purposes. LG617 - XLE Lab

10. A closer look at XLE • Grammar architecture? • Inspecting a basic grammar .lfg file • Inspecting the config file? • Inspecting a rule • Inspecting a lexical entry • XLE interface • XLE vs LFG notations LG617 - XLE Lab

11. LFG Grammar (rules, templates) Other Finite State Tools Lexicon(s) (Hand-written Or Automatically Extracted) Grammar Resources (parsing and generating) Tokenizer Morpholo- gical Analyser FST A closer look at XLE :: Basic Grammar Architecture :: LG617 - XLE Lab

12. A closer look at XLE :: Inspecting a grammar file :: LG617 - XLE Lab

13. A closer look at XLE :: XLE interface :: Packed representa-tion of f-structures C-structure Representa-tion logical choices (in cases of ambiguity) f-structure % parse {Mary saw the boys with the telescope} parsing {Mary saw the boys with the telescope} 2 solutions, 0.01 CPU seconds, 23 subtrees unified LG617 - XLE Lab

14. A closer look at XLE :: XLE vs LFG Notations :: LFG notation XLE-equivalent Description ↑ ^ f-structure metavariable ↓ ! f-structure metavariable = = defining equality ≡ = meta-category definition =c =c or =C constraining equality ∈ $ set membership ¬ ~ negation (complementation) d d existential constraint (standard notation) ∃ d d existential constraint (Sadler) ← <- off-path constraint → -> off-path constraint ⊑ << subsumption (subsumes) ⊒ >> subsumption (is subsumed by) { a | b | c | ... | z } { a | b | c | ... | z } disjunction ( a ) { a } optional f-structure constraint LG617 - XLE Lab

15. Hands-on Session  LG617 - XLE Lab

16. References / Sources • ParGram http://www2.parc.com/isl/groups/nltt/pargram/ • XLE Web Interface Documentation: http://maximos.aksis.uib.no/Aksis-wiki/XLE-Web • XLE Documentation http://www2.parc.com/isl/groups/nltt/xle/doc/xle_toc.html • Powerset http://www.powerset.com/ LG617 - XLE Lab

17. Thank you! For more information and updates on the progress of the project visit http://privatewww.essex.ac.uk/~achats/projects/greekgram/index.html LG617 - XLE Lab