The GF Resource Grammar Library Version 1.0 Author: Aarne Ranta Last update: %%date(%c) % NOTE: this is a txt2tags file. % Create an html file from this file using: % txt2tags --toc clt2006.txt %!target:html %!postproc(html): #NEW #NEW ==Plan== Purpose Background Coverage Structure How to use How to implement a new language How to extend the API #NEW ==Purpose== ===Library for applications=== High-level access to grammatical rules E.g. //You have k new messages// rendered in ten languages //X// ``` render X (Have (You (Number (k (New Message))))) ``` Usability for different purposes - translation systems - software localization - dialogue systems - language teaching #NEW ===Grammar as parser=== Often in NLP, a grammar is just high-level code for a parser. But writing a grammar can be inadequate for parsing: - too much manual work - too inefficient - not robust - too ambiguous Moreover, a grammar fine-tuned for parsing may not be reusable - for generation - for specialized grammars - as library #NEW ===Grammar as language definition=== Linguistic ontology: **abstract syntax** E.g. adjectival modification ``` AdjCN : AP -> CN -> CN ; ``` Rendering in different languages: **concrete syntax** Resource grammars have generation perspective, rather than parsing - abstract syntax serves as a key to expressions in different languages #NEW ===Usability by non-linguists=== Division of labour: resource grammars hide linguistic details - ``AdjCN : AP -> CN -> CN`` hides agreement, word order,... Presentation: "school grammar" concepts, dictionary-like conventions ``` bird_N = reg2N "Vogel" "Vögel" masculine ``` API = Application Programmer's Interface Documentation: ``gfdoc`` - produces html from gf IDE = Interactive Development Environment (forthcoming) - library browser and syntax editor for grammar writing Example-based grammar writing ``` render Ita (parse Eng "you have k messages") ``` #NEW ===Scientific interest=== Linguistics - definition of linguistic ontology - describing language on this level of abstraction - coping with different problems in different languages - sharing concrete-syntax code between languages - creating a resource for other NLP applications Computer science - datastructures for grammar rules - type systems for grammars - algorithms: parsing, generation, grammar compilation - domain-specific programming language (GF) - module system #NEW ==Background== ===History=== 2002: v. 0.2 - English, French, German, Swedish 2003: v. 0.6 - module system - added Finnish, Italian, Russian - used in KeY 2005: v. 0.9 - tenses - added Danish, Norwegian, Spanish; no German - used in WebALT 2006: v. 1.0 - approximate CLE coverage - reorganized module system and implementation - not yet (4/3/2006) for Danish and Russian #NEW ===Authors=== Janna Khegai (Russian modules, forthcoming), Bjorn Bringert (many Swadesh lexica), Inger Andersson and Therese Söderberg (Spanish morphology), Ludmilla Bogavac (Russian morphology), Carlos Gonzalia (Spanish cardinals), Partik Jansson (Swedish cardinals), Aarne Ranta. We are grateful for contributions and comments to several other people who have used this and the previous versions of the resource library, including Ana Bove, David Burke, Lauri Carlson, Gloria Casanellas, Karin Cavallin, Hans-Joachim Daniels, Kristofer Johannisson, Anni Laine, Wanjiku Ng'ang'a, Jordi Saludes. #NEW ===Related work=== CLE (Core Language Engine, [Book 1992 http://mitpress.mit.edu/catalog/item/default.asp?tid=7739&ttype=2]) - English, Swedish, French, Danish - uses Definita Clause Grammars, implementation in Prolog - coverage for the ATIS corpus, [Spoken Language Translator (2001) http://www.cambridge.org/uk/catalogue/catalogue.asp?isbn=0521770777] - grammar specialization via explanation-based learning #NEW ===Slightly less related work=== [LinGO Grammar Matrix http://www.delph-in.net/matrix/] - English, German, Japanese, Spanish, ... - uses HPSG, implementation in LKB - a check list for parallel grammar implementations [Pargram http://www2.parc.com/istl/groups/nltt/pargram/] - Aimed: Arabic, Chinese, English, French, German, Hungarian, Japanese, Malagasy, Norwegian, Turkish, Urdu, Vietnamese, and Welsh - uses LFG - one set of big grammars, transfer rules Rosetta Machine Translation ([Book 1994 http://citeseer.ist.psu.edu/181924.html]) - Dutch, English, French - uses M-grammars, compositional translation inspired by Montague - compositional transfer rules #NEW ==Coverage== ===Languages=== The current GF Resource Project covers ten languages: - ``Dan``ish - ``Eng``lish - ``Fin``nish - ``Fre``nch - ``Ger``man - ``Ita``lian - ``Nor``wegian (bokmål) - ``Rus``sian - ``Spa``nish - ``Swe``dish In addition, parts (morphology) of Arabic, Estonian, Latin, and Urdu API 1.0 not yet implemented for Danish and Russian #NEW ===Morphology and lexicon=== Complete inflection engine - all word classes - all forms - all inflectional paradigms Basic lexicon - 100 structural words - 340 content words, mainly for testing - these include the 207 [Swadesh words http://en.wiktionary.org/wiki/Swadesh_List] It is more important to enable lexicon extensions than to provide a huge lexicon. - technical lexica can have very special words, which tend to be regular #NEW ===Syntactic structures=== Texts: sequences of phrases with punctuation Phrases: declaratives, questions, imperatives, vocatives Tense, mood, and polarity: present, past, future, conditional ; simultaneous, anterior ; positive, negative Questions: yes-no, "wh" ; direct, indirect Clauses: main, relative, embedded (subject, object, adverbial) Verb phrases: intransitive, transitive, ditransitive, prepositional Noun phrases: proper names, pronouns, determiners, possessives, cardinals and ordinals #NEW ===Quantitative measures=== 67 categories 150 abstract syntax combination rules 100 structural words 340 content words in a test lexicon 35 kLines of source code (4/3/2006): ``` abstract 1131 english 2344 german 2386 finnish 3396 norwegian 1257 swedish 1465 scandinavian 1023 french 3246 -- Besch + Irreg + Morpho 2111 italian 7797 -- Besch 6512 spanish 7120 -- Besch 5877 romance 1066 ``` #NEW ==Structure of the API== ===Language-independent ground API=== [Lang.png] #NEW ===The structure of a text sentence=== ``` John walks. TFullStop : Phr -> Text -> Text | TQuestMark, TExclMark (PhrUtt : PConj -> Utt -> Voc -> Phr | PhrYes, PhrNo, ... NoPConj | but_PConj, ... (UttS : S -> Utt | UttQS, UttImp, UttNP, ... (UseCl : Tense -> Anter -> Pol -> Cl -> S TPres ASimul PPos (PredVP : NP -> VP -> Cl | ImpersNP, ExistNP, ... (UsePN : PN -> NP john_PN) (UseV : V -> VP | ComplV2, UseComp, ... walk_V)))) NoVoc) | VocNP, please_Voc, ... TEmpty ``` #NEW ===Structure in syntax editor=== [editor.png] #NEW ===Language-dependent paradigm modules=== ====Regular paradigms==== Every language implements these regular patterns that take "dictionary forms" as arguments. ``` regN : Str -> N regA : Str -> A regV : Str -> V ``` Their usefulness varies. For instance, they all are quite good in Finnish and English. In Swedish, less so: ``` regN "val" ---> val, valen, valar, valarna ``` Initializing a lexicon with ``regX``s is usually a good starting point in grammar development. #NEW ====Regular paradigms==== In Swedish, giving the gender of ``N`` improves a lot ``` regGenN "val" neutrum ---> val, valet, val, valen ``` There are also special constructs taking other forms: ``` mk2N : (nyckel,nycklar : Str) -> N mk1N : (bilarna : Str) -> N irregV : (dricka, drack, druckit : Str) -> V ``` Regular verbs are actually implemented the [Lexin http://lexin.nada.kth.se/sve-sve.shtml] way ``` regV : (talar : Str) -> N ``` #NEW ====Worst-case paradigms==== To cover all situations, worst-case paradigms are given. E.g. Swedish ``` mkN : (apa,apan,apor,aporna : Str) -> N mkA : (liten, litet, lilla, små, mindre, minst, minsta : Str) -> A mkV : (supa,super,sup,söp,supit,supen : Str) -> V ``` #NEW ====Irregular words==== Iregular words in ``IrregX``, e.g. Swedish: ``` draga_V : V = mkV (variants { "dra"; "draga"}) (variants { "drar" ; "drager"}) (variants { "dra" ; "drag" }) "drog" "dragit" "dragen" ; ``` Goal: eliminate the user's need of worst-case functions. #NEW ===Language-dependent syntax extensions=== Syntactic structures that are not shared by all languages. Not implemented yet. Candidates: - ``Nor`` post-possessives: ``bilen min`` - ``Fre`` question forms: ``est-ce que tu dors ?`` #NEW ===Special-purpose APIs=== Mathematical Multimodal Present Minimal Shallow #NEW ===How to use the resource as top-level grammar=== ===Compiling=== It is a good idea to compile the library, so that it can be opened faster ``` GF/lib/resource-1.0% make writes GF/lib/alltenses GF/lib/present GF/lib/resource-1.0/langs.gfcm ``` If you don't intend to change the library, you never need to process the source files again. Just do some of ``` gf -nocf langs.gfcm -- all 8 languages gf -nocf -path=alltenses:prelude alltenses/LangSwe.gfc -- Swedish only gf -nocf -path=alltenses:prelude present/LangSwe.gfc -- Swedish only, present tense only ``` #NEW ===Parsing=== The default parser does not work! The MCFG parser works in some languages, after waiting appr. 20 seconds ``` p -mcfg -lang=LangEng -cat=S "I would see her" p -mcfg -lang=LangSwe -cat=S "jag skulle se henne" ``` Parsing in ``present/`` versions is quicker. #NEW ===Treebank generation=== Multilingual treebank entry = tree + linearizations Some examples on treebank generation, assuming ``langs.gfcm`` ``` gr -cat=S -number=10 -cf | tb -- 10 random S gt -cat=Phr -depth=4 | tb -xml | wf ex.xml -- all Phr to depth 4, into file ex.xml ``` Regression testing ``` rf ex.xml | tb -c -- read treebank from file and compare to present grammars ``` Updating a treebank ``` rf old.xml | tb -trees | tb -xml | wf new.xml -- read old from file, write new to file ``` #NEW ===Treebank-based parsing=== Brute-force method that helps if real parsing is more expensive. ``` make treebank -- make treebank with all languages gf -treebank langs.xml -- start GF by reading the treebank > ut -strings -treebank=LangIta -- show all Ita strings > ut -treebank=LangIta -raw "Quello non si romperebbe" -- look up a string > i -nocf langs.gfcm -- read grammar to be able to linearize > ut -treebank=LangIta "Quello non si romperebbe" | l -multi -- translate to all ``` #NEW ===Morphology=== Use morphological analyser ``` gf -nocf -retain -path=alltenses:prelude alltenses/LangSwe.gf > ma "jag kan inte höra vad du säger" ``` Try out a morphology quiz ``` > mq -cat=V ``` Try out inflection patterns ``` gf -retain -path=alltenses:prelude alltenses/ParadigmsSwe.gfr > cc regV "lyser" ``` #NEW ===Syntax editing=== We start a demo by ``` gfeditor langs.gfcm [editor.png] #NEW ===Efficient parsing via application grammar=== Get rid of discontinuous constituents Examples: ``mathematical/Predication``, ``examples/bronzeage`` #NEW ==How to use as library== ===Specialization through parametrized modules=== The application grammar is implemented with reference to the resource API Individual languages are instantiations Example: [tram ../../../examples/tram/TramI.gf] #NEW ===Compile-time transfer=== Instead of parametrized modules: select resource functions differently for different languages Example: imperative vs. infinitive in mathematical exercises #NEW ===A natural division into modules=== Lexicon in language-dependent moduls Combination rules in a parametrized module #NEW ===Example-based grammar writing=== Example: [animal ../../../examples/animal/QuestionsI.gfe] #NEW ==How to implement a new language== See [Resource-HOWTO Resource-HOWTO.html] ==Ordinary modules== Write a concrete syntax module for each abstract module in the API Write a ``Paradigms`` module Examples: English, Finnish, German, Russian #NEW ==Parametrized modules== Examples: Romance (French, Italian, Spanish), Scandinavian (Danish, Norwegian, Swedish) Write a ``Diff`` interface for a family of languages Write concrete syntaxes as functors opening the interface Write separate ``Paradigms`` modules for each language Advantages: - easier maintenance of library - insights into language families Problems: - more abstract thinking required - individual grammars may not come out optimal in elegance and efficiency #NEW ===The core of the API=== Everything else is variations of this ``` cat Cl ; -- clause VP ; -- verb phrase V2 ; -- two-place verb NP ; -- noun phrase CN ; -- common noun Det ; -- determiner AP ; -- adjectival phrase fun PredVP : NP -> VP -> Cl ; -- predication ComplV2 : V2 -> NP -> VP ; -- complementization DetCN : Det -> CN -> NP ; -- determination ModCN : AP -> CN -> CN ; -- modification ``` #NEW ===The core of the API=== This [toy Latin grammar latin.gf] shows in a nutshell how the core can be implemented. Use this API as a first approximation when designing the parameter system of a new language. #NEW ===How to proceed=== + put up a directory with dummy modules by copying from e.g. English and commenting out the contents + so you will have a compilable ``LangX`` all the time + start with nouns and their inflection + proceed to verbs and their inflection + add some noun phrases + implement predication #NEW ==How to extend the API== Extend old modules or add a new one? Usually better to start a new one: then you don't have to implement it for all languages at once. Exception: if you are working with a language-specific API extension, you can work directly in that module.