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593 lines
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HTML
593 lines
12 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN">
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<html><head><title></title></head>
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<body bgcolor="#ffffff" text="#000000">
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<center>
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<img src="gf-logo.gif">
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<h1>GF Resource Grammar Library</h1>
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<p>
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Second Version, Gothenburg, 18 February 2005
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<br>
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First Draft, Gothenburg, 7 February 2005
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</p><p>
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Aarne Ranta
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</p><p>
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<tt>aarne@cs.chalmers.se</tt>
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</p></center>
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<h2>GF = Grammatical Framework</h2>
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A grammar formalism based on functional programming and type theory.
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<p>
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Designed to be nice for <i>ordinary programmers</i> to use.
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<p>
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Mission: to make natural-language applications available for
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ordinary programmers, in tasks like
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<ul>
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<li> software documentation
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<li> domain-specific translation
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<li> human-computer interaction
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<li> dialogue systems
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</ul>
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Thus <i>not</i> primarily another theoretical framework for
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linguists.
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<h2>Language + Libraries</h2>
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Writing natural language grammars still requires
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theoretical knowledge about the language.
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<p>
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Which kind of programmer is easier to find?
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<ul>
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<li> one who can write a sorting algorithm
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<li> one who can write a grammar for Swedish determiners
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</ul>
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<p>
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In main-stream programming, sorting algorithms are not
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written by hand but taken from <b>libraries</b>.
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<p>
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In the same way, we want to create grammar libraries that encapsulate
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basic linguistic facts.
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<p>
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Cf. the Java success story: the language is just a half of the
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success - libraries are another half.
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<h2>Example of library-based grammar writing</h2>
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To define Swedish definite phrases form scratch:
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<pre>
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</pre>
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To use a library function for Swedish definite phrases:
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<pre>
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</pre>
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<!-- NEW -->
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<h2>Questions in grammar library design</h2>
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What should there be in the library?
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<br>
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<li> morphology, lexicon, syntax, semantics,...
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<p>
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How do we organize and present the library?
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<br>
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<li> division into modules, level of granularity
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<br>
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<li> "school grammar" vs. sophisticated linguistic concepts
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<p>
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Where do we get the data from?
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<br>
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<li> automatic extraction or hand-writing?
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<br>
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<li> reuse of existing resources?
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<p>
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Extra constraint: we want open-source free software.
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<h2>The scope of the resource grammar library</h2>
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All morphological paradigms
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<p>
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Basic lexicon of structural, common, and irregular words
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<p>
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Basic syntactic structures
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<p>
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Currently <i>no</i> semantics,
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<i>no</i> language-specific structures if not
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necessary for expressivity.
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<h2>Success criteria</h2>
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Grammatical correctness
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<p>
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Semantic coverage: you can express whatever you want.
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<p>
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Usability as library for non-linguists.
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<p>
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(Bonus for linguists:) nice generalizations w.r.t. language
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families, using the module system of GF.
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<h2>These are not our success criteria</h2>
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Language coverage: you can parse all expressions. Example:
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the French <i>passé simple</i> tense, although covered by the
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morhology, is not used in the language-independent API, but
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only the <i>passé composé</i> is.
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<p>
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Semantic correctness
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<pre>
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colourless green ideas sleep furiously
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the time is seventy past forty-two
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</pre>
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<p>
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(Warning for linguists:) theoretical innovation in
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syntax
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<h2>So where is semantics?</h2>
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GF incorporates a <b>Logical Framework</b> and is therefore
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capable of expressing logical semantics <i>à la</i> Montague
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or any other flavour, including anaphora and discourse.
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<p>
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But we do <i>not</i> believe semantics can be given once and
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for all for a natural language.
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<p>
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Instead, we expect semantics to be given in
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<b>application grammars</b> built on semantic models
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of different domains.
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<p>
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Example application: number theory
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<pre>
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fun Even : Nat -> Prop ; -- a mathematical predicate
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lin Even = predA (regA "even") ; -- English translation
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lin Even = predA (regA "pair") ; -- French translation
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lin Even = predA (regA "jämn") ; -- Swedish translation
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</pre>
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How could the resource predict that just <i>these</i>
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translations are correct in this domain?
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<p>
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Application grammars are built by experts of these domains
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who - thanks to resource grammars - do no more need to be
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experts in linguistics.
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<h2>Languages</h2>
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The current GF Resource Project covers ten languages:
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<ul>
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<li><tt>Dan</tt>ish
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<li><tt>Eng</tt>lish
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<li><tt>Fin</tt>nish
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<li><tt>Fre</tt>nch
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<li><tt>Ger</tt>man
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<li><tt>Ita</tt>lian
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<li><tt>Nor</tt>wegian
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<li><tt>Rus</tt>sian
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<li><tt>Spa</tt>nish
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<li><tt>Swe</tt>dish
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</ul>>
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The first three letters (<tt>Dan</tt> etc) are used in grammar module names
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<h2>Library structure 1: language-independent API</h2>
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<li> syntactic <tt>Categories</tt> (parts of speech, word classes), e.g.
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<pre>
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V ; NP ; CN ; Det ; -- verb, noun phrase, common noun, determiner
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</pre>
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<li> <tt>Rules</tt> for combining words and phrases, e.g.
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<pre>
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DetNP : Det -> CN -> NP ; -- combine Det and CN into NP
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</pre>
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<li> the most common <tt>Structural</tt> words (determiners,
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conjunctions, pronouns), e.g.
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<pre>
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and_Conj : Conj ;
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</pre>
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<h2>Library structure 2: language-dependent modules</h2>
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<li> morphological <tt>Paradigms</tt>, e.g.
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<pre>
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mkN : Str -> Str -> Str -> Str -> Gender -> N ; -- worst-case nouns
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mkN : Str -> N ; -- regular nouns
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</pre>
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<li> irregular <tt>Verbs</tt>, e.g.
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<pre>
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angripa_V = irregV "angripa" "angrep" "angripit" ;
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</pre>
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<li> <tt>Lexicon</tt> of frequent words
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<pre>
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man_N = mkN "man" "mannen" "män" "männen" masculine ;
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</pre>
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<li> <tt>Ext</tt>ended syntax with language-specific rules
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<pre>
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PassBli : V2 -> NP -> VP ; -- bli överkörd av ngn
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</pre>
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<h2>How much can be language-independent?</h2>
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For the ten languages we have considered, it <i>is</i> possible
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to implement the current API.
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<p>
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Reservations:
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<ul>
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<li> does not necessarily extend to all other languages
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<li> does not necessarily cover the most idiomatic expressions
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of each language
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<li> may not be the easiest API to implement (e.g. negation and
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inversion with <i>do</i> in English suggest that some other
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structure would be more natural)
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<li> does not guarantee that same structure has the same semantics
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in different languages
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<p>
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<!-- NEW -->
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<h2>Library structure: language-independent API</h2>
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<center>
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<img src="Resource.gif">
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</center>
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<!-- NEW -->
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<h2>Library structure: test bed for the language-independent API</h2>
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<center>
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<img src="Lang.gif">
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</center>
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<h2>API documentation</h2>
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<a href="Categories.html">Categories</a>
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<p>
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<a href="Rules.html">Rules</a>
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<p>
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Alternative views on sentence formation:
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<a href="Clause.html">Clause</a>,
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<a href="Verbphrase.html">Verbphrase</a>
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<p>
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<a href="Structural.html">Structural</a>
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<p>
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<a href="Time.html">Time</a>
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<p>
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<a href="Basic.html">Basic</a>
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<p>
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<a href="Lang.html">Lang</a>
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<p>
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<!-- NEW -->
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<h2>Paradigms documentation</h2>
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<a href="ParadigmsEng.html">English paradigms</a>
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<br>
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<a href="BasicEng.html">example use of English oaradigms</a>
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<br>
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<a href="VerbsEng.html">English verbs</a>
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<p>
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<a href="ParadigmsFre.html">French paradigms</a>
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<br>
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<a href="BasicFre.html">example use of French paradigms</a>
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<br>
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<a href="VerbsFre.html">French verbs</a>
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<p>
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<a href="ParadigmsSwe.html">Swedish paradigms</a>
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<br>
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<a href="BasicSwe.html">example use of Swedish paradigms</a>
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<br>
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<a href="VerbsSwe.html">Swedish verbs</a>
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<h2>Use as top-level grammar: testing</h2>
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Import a set of $LangX$ grammars:
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<pre>
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i english/LangEng.gf
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i swedish/LangSwe.gf
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</pre>
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Test with random generation, translation, morphological analysis...
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<pre>
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</pre>
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<h2>Use as top-level grammar: language learning quizzes</h2>
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Morpho quiz with words:
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<pre>
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</pre>
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Morpho quiz with phrases:
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<pre>
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</pre>
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Translation quiz with sentences:
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<pre>
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</pre>
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<h2>Use as library</h2>
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Import directly by <tt>open</tt>:
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<pre>
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concrete AppNor of App = open LangNor, ParadigmsNor in {...}
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</pre>
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No more dummy <tt>reuse</tt> modules and bulky <tt>.gfr</tt> files!
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<p>
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If you need to convert resource category records to/from strings, use
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<pre>
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Predef.toStr : (L : Type) -> L -> Str ;
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</pre>
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<tt>L</tt> must be a linearization type. For instance,
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<pre>
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toStr LangNor.CN (ModAP (PositADeg old_ADeg) (UseN car_N))
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---> "gammel bil"
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</pre>
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<h2>Use as library through parser</h2>
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Use the parser when developing a resource.
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<pre>
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> p -cat=S -v "jag ska åka till Chalmers"
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unknown tokens [TS "åka",TS "Chalmers"]
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> p -cat=S "jag ska gå till Danmark"
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UseCl (PosTP TFuture ASimul)
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(AdvCl (SPredV i_NP go_V)
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(AdvPP (PrepNP to_Prep (UsePN (PNCountry Denmark)))))
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</pre>
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Extend vocabulary at need.
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<pre>
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åka_V = lexV "åker" ;
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Chalmers = regPN "Chalmers" neutrum ;
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</pre>
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<!-- NEW -->
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<h2>Example application: a small translation system</h2>
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You can say things like the following:
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<pre>
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who chases mice ?
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whom does the lion chase ?
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the dog chases cats
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</pre>
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Source modules:
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<p>
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<a href=example/Animals.gf>Animals</a>
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<p>
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<a href=example/AnimalsEng.gf>AnimalsEng</a>
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<p>
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<a href=example/AnimalsFre.gf>AnimalsFre</a>
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<p>
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<a href=example/AnimalsSwe.gf>AnimalsSwe</a>
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<h2>Compiling the example application</h2>
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The resources are bulky, and it takes a therefore a lot of
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time and memory to load the grammars. However, they can be
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compiled into the <tt>gfcm</tt>
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(<b>GF canonical multilingual</b>) format,
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which is almost one thousand times smaller and faster to load
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for this set of grammars.
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<p>
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Just issue the following GF commands
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<pre>
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i -src AnimalsEng.gf ;; s
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i -src AnimalsFre.gf ;; s
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i -src AnimalsSwe.gf ;; s
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pm | wf animals.gfcm
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</pre>
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and you get an end-user grammar <tt>animals.gfcm</tt>.
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<p>
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You can also write the commands in a <tt>gfs</tt> (<b>GF script</b>)
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file, say
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<a href=mkAnimals.gfc><tt>mkAnimals.gfs</tt></a>,
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and then call GF with
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<pre>
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gf <mkAnimals.gfs
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</pre>
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<!-- NEW -->
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<h2>Further simplifications of the application grammar</h2>
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Step 1: use a simplified access to present-tense sentences,
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<tt>SentenceX</tt> (to be written...)
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<p>
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Step 2: factor out the categories and purely combinational
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rules into an <tt>incomplete</tt> module (to be shown... but
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this does not work for French, which uses different structures:
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e.g. <i>Qui aime les lions ?</i> with a definite phrase
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where English has <i>Who loves lions?</i>
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<!-- NEW -->
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<h2>Implementation details: the structure of low-level files</h2>
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<center>
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<img src="Low.gif">
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</center>
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<!-- NEW -->
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<h2>The use of parametric modules</h2>
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In two language families:
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<ul>
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<li> Romance: French, Italian, Spanish
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<li> Scandinavian: Danish, Norwegian, Swedish
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</ul>
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<center>
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<img src="Scand.gif">
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</center>
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<!-- NEW -->
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<h2>Current status</h2>
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<table border=1>
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<tr><td>Language</td> <td>v0.6</td> <td>API</td> <td>Paradigms</td> <td>Basic lex</td> <td>Verbs</td></tr>
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<tr><td>Danish</td> <td> </td> <td>X</td> <td> </td> <td> </td> <td> </tr>
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<tr><td>English</td> <td>X</td> <td>X</td> <td>X</td> <td>X</td> <td>X</tr>
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<tr><td>Finnish</td> <td>X</td> <td> </td> <td> </td> <td> </td> <td> </tr>
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<tr><td>French</td> <td>X</td> <td>*</td> <td>X</td> <td>X</td> <td>X</tr>
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<tr><td>German</td> <td>X</td> <td> </td> <td>*</td> <td> </td> <td> </tr>
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<tr><td>Italian</td> <td>X</td> <td>*</td> <td>*</td> <td> </td> <td>*</tr>
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<tr><td>Norwegian</td> <td> </td> <td>X</td> <td> </td> <td> </td> <td> </tr>
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<tr><td>Russian</td> <td>X</td> <td>*</td> <td>*</td> <td> </td> <td> </tr>
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<tr><td>Spanish</td> <td> </td> <td>*</td> <td> </td> <td> </td> <td>*</tr>
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<tr><td>Swedish</td> <td>X</td> <td>X</td> <td>X</td> <td>X</td> <td>X</tr>
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</table>
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<!-- NEW -->
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<h2>Obtaining it</h2>
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Now on CVS at Chalmers:
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<pre>
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cvs -d /users/cs/aarne/cvs checkout GF2.0/lib
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</pre>
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<p>
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To appear later at GF Homepage:<p>
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<a href="http://www.cs.chalmers.se/%7Eaarne/GF">
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<tt>http://www.cs.chalmers.se/~aarne/GF</tt></a>
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</p></body></html> |