Transition-based dependency parsing as latent-variable constituent parsing

We provide a theoretical argument that a common form of projective transition-based dependency parsing is less powerful than constituent parsing using latent variables. The argument is a proof that, under reasonable assumptions, a transition-based dependency parser can be converted to a latent-variable context-free grammar producing equivalent structures.Postprin

Unbounded Recursion in Two Dimensions, Where Syntax and Prosody Meet

Both syntax and prosody seem to require structures with unbounded branching, something that is not immediately provided by multiple context free grammars or other equivalently expressive formalisms. That extension is easy, and does not disrupt an appealing model of prosody/syntax interaction. Rather than computing prosodic and syntactic structures independently and then selecting optimally corresponding pairs, prosodic structures can be computed directly from the syntax, eliminating alignment issues and the need for bracket-insertion or other ad hoc devices. To illustrate, a simple model of prosodically-defined Irish pronoun displacement is briefly compared to previous proposals

Syntactic Structures: formal considerations 60 years later

Chomsky (1955), The Logical Structure of Linguistic Theory (henceforth LSLT), laid out in great detail the formal foundations for a rigorous new way of looking at language scientifcally, transformational generative grammar. This awesome accomplishment was announced to the world in Chomsky (1957), Syntactic Structures (henceforth SS), a publication that revolutionized the feld, or really, created a new feld. Needless to say, syntactic theory has undergone vast changes since then, but certain fundamental ideas, and even a few technical details, persist. In this article, I will briefly discuss some instances of each sort. ---DOI: http://dx.doi.org/10.31513/linguistica.2017.v13n2a14026Chomsky (1955), The Logical Structure of Linguistic Theory (henceforth LSLT), laid out in great detail the formal foundations for a rigorous new way of looking at language scientifcally, transformational generative grammar. This awesome accomplishment was announced to the world in Chomsky (1957), Syntactic Structures (henceforth SS), a publication that revolutionized the feld, or really, created a new feld. Needless to say, syntactic theory has undergone vast changes since then, but certain fundamental ideas, and even a few technical details, persist. In this article, I will briefly discuss some instances of each sort. ---DOI: http://dx.doi.org/10.31513/linguistica.2017.v13n2a1402

Recognition is not parsing — SPPF-style parsing from cubic recognisers

AbstractIn their recogniser forms, the Earley and RIGLR algorithms for testing whether a string can be derived from a grammar are worst-case cubic on general context free grammars (CFG). Earley gave an outline of a method for turning his recognisers into parsers, but it turns out that this method is incorrect. Tomita’s GLR parser returns a shared packed parse forest (SPPF) representation of all derivations of a given string from a given CFG but is worst-case unbounded polynomial order. The parser version of the RIGLR algorithm constructs Tomita-style SPPFs and thus is also worst-case unbounded polynomial order. We have given a modified worst-case cubic GLR algorithm, that, for any string and any CFG, returns a binarised SPPF representation of all possible derivations of a given string. In this paper we apply similar techniques to develop worst-case cubic Earley and RIGLR parsing algorithms

Parsing Based on Random Context Grammars

Tato bakalářská práce popisuje gramatiku s nahodilým kontextem a implementaci aplikace, která bude konvertovat gramatiku (respektující LL podmínku) na ekvivalentní bezkontextovou gramatiku (také splňující podmínku LL). Výslednou gramatiku je možné použít ve stávajících generátorech parseru, který přijme yacc-kompatibilní formát. Tato práce používá GNU Bison generátor, pro který byl zavedený zapouzdřený skript. Potenciální výhodou gramatiky s nahodilým kontextem je dokázaný úspornější zápis oproti bezkontextové gramatiky pro některé jazyky.This thesis describes a random context grammar and the implementation of an application which will convert this grammar (respecting the LL condition) to an equivalent context-free grammar (also satisfying the LL condition). The resulting grammar can be used in the existing parser generator that accepts a yacc-compatible format. This thesis uses the GNU Bison generator, for which the encapsulated script was introduced. The potential advantage of random context grammar consists in the proven efficient description compared to context-free grammar for some languages.

Multiple Context-Free Tree Grammars: Lexicalization and Characterization

Multiple (simple) context-free tree grammars are investigated, where "simple" means "linear and nondeleting". Every multiple context-free tree grammar that is finitely ambiguous can be lexicalized; i.e., it can be transformed into an equivalent one (generating the same tree language) in which each rule of the grammar contains a lexical symbol. Due to this transformation, the rank of the nonterminals increases at most by 1, and the multiplicity (or fan-out) of the grammar increases at most by the maximal rank of the lexical symbols; in particular, the multiplicity does not increase when all lexical symbols have rank 0. Multiple context-free tree grammars have the same tree generating power as multi-component tree adjoining grammars (provided the latter can use a root-marker). Moreover, every multi-component tree adjoining grammar that is finitely ambiguous can be lexicalized. Multiple context-free tree grammars have the same string generating power as multiple context-free (string) grammars and polynomial time parsing algorithms. A tree language can be generated by a multiple context-free tree grammar if and only if it is the image of a regular tree language under a deterministic finite-copying macro tree transducer. Multiple context-free tree grammars can be used as a synchronous translation device.Comment: 78 pages, 13 figure