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26.02.2009 LG617 - XLE Lab 1
Kakia Chatsiou A brief introduction to XLE
LG617 A brief introduction to XLE
Kakia Chatsiou
[email protected] of Language and Linguistics
University of Essex
26.02.2009 LG617 - XLE Lab 2
Kakia Chatsiou A brief introduction to XLE
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
26.02.2009 LG617 - XLE Lab 3
Kakia Chatsiou A brief introduction to XLE
About XLE
• XLE stands for Xerox Linguistics Environment• 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 parsing and generation• Includes tools for various grammar development activities
(such as analysing performance, test-suites)
26.02.2009 LG617 - XLE Lab 4
Kakia Chatsiou A brief introduction to XLE
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 PowerPowerset set
26.02.2009 LG617 - XLE Lab 5
Kakia Chatsiou A brief introduction to XLE
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
26.02.2009 LG617 - XLE Lab 6
Kakia Chatsiou A brief introduction to XLE
Participating Members
PARC, CAChinese, English,
French
EssexGreek, Welsh
ManchesterArabic
OxfordMalagasy
DCU, IrelandChinese, English, French, German,
Japanese, Spanish
Fuji XEROXJapanese
Bergen, NorwayGeorgian, Norwegian, Tigrinya
Ho Chi MinchVietnamese
DebrecenHungarian
IMS, StuttgartGerman
KonstanzUrdu
Sabanci, IstanbulTurkish
Where is XLE used? :: ParGram Project ::
26.02.2009 LG617 - XLE Lab 7
Kakia Chatsiou A brief introduction to XLE
• a Silicon Valley Company, currently building a transformative consumer search enginesearch 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 )
Where is XLE used? :: Powerset Search Engine ::
26.02.2009 LG617 - XLE Lab 8
Kakia Chatsiou A brief introduction to XLE
Where is XLE used? :: Powerset Search Engine ::
26.02.2009 LG617 - XLE Lab 10
Kakia Chatsiou A brief introduction to XLE
• 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.
Where is XLE used? :: The XLE Web Interface ::
26.02.2009 LG617 - XLE Lab 11
Kakia Chatsiou A brief introduction to XLE
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
26.02.2009 LG617 - XLE Lab 12
Kakia Chatsiou A brief introduction to XLE
Other Finite State Tools
Tokenizer
Morpholo-gical
AnalyserFST
Lexicon(s)(Hand-written
OrAutomatically
Extracted)
LFG Grammar
(rules, templates)
Grammar Resources(parsing
and generating)
A closer look at XLE :: Basic Grammar Architecture ::
26.02.2009 LG617 - XLE Lab 13
Kakia Chatsiou A brief introduction to XLE
A closer look at XLE :: Inspecting a grammar file ::
26.02.2009 LG617 - XLE Lab 14
Kakia Chatsiou A brief introduction to XLE
A closer look at XLE :: XLE interface ::
C-structur
e
f-structur
e
Packed representa-tion of f-structures
Representa-tion logical
choices (in cases of
ambiguity)
% 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
26.02.2009 LG617 - XLE Lab 15
Kakia Chatsiou A brief introduction to XLE
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
A closer look at XLE :: XLE vs LFG Notations ::
26.02.2009 LG617 - XLE Lab 16
Kakia Chatsiou A brief introduction to XLE
Hands-on Session
26.02.2009 LG617 - XLE Lab 17
Kakia Chatsiou A brief introduction to XLE
References / Sources
• ParGramhttp://www2.parc.com/isl/groups/nltt/pargram/
• XLE Web Interface Documentation: http://maximos.aksis.uib.no/Aksis-wiki/XLE-Web
• XLE Documentationhttp://www2.parc.com/isl/groups/nltt/xle/doc/xle_toc.html
• Powersethttp://www.powerset.com/
26.02.2009 LG617 - XLE Lab 18
Kakia Chatsiou A brief introduction to XLE
Thank you!
For more information and updates on the progress of the project visit
http://privatewww.essex.ac.uk/~achats/projects/greekgram/index.html