From functional specification to syntactic structures: systemic grammar and tree adjoining grammar

In this paper we provide an implementation strategy to map a functional specification of an utterance into a syntactically well-formed sentence. We do this by integrating the functional and the syntactic perspectives on language, which we take to be exemplified by systemic grammars and tree adjoining grammars (TAGs) respectively. From systemic grammars we borrow the use of networks of choices to classify the set of possible constructions. The choices expressed in an input are mapped by our generator to a syntactic structure as defined by a TAG. We argue that the TAG structures can be appropriate structural units of realization in an implementation of a generator based on systemic grammar and also that a systemic grammar provides an effective means of deciding between various syntactic possibilities expressed in a TAG grammar. We have developed a generation strategy which takes advantage of what both paradigms offer to generation, without compromising either.     

Compact coding of syntax tables

A method for constructing compact syntax tables in three steps is presented. First, the rules of a grammar are mapped into a syntax graph, from which five syntactic forms are defined. Secondly, the grammar expressed in these syntactic forms is mapped into data structures. Finally, from the data structures, the compact syntax table of the grammar is constructed.     

Syntactic Calculus with Dependent Types

The aim of this study is to look at the the syntactic calculus of Bar-Hillel and Lambek, including semantic interpretation, from the point of view of constructive type theory. The syntactic calculus is given a formalization that makes it possible to implement it in a type-theoretical proof editor. Such an implementation combines formal syntax and formal semantics, and makes the type-theoretical tools of automatic and interactive reasoning available in grammar.In the formalization, the use of the dependent types of constructive type theory is essential. Dependent types are already needed in the semantics of ordinary Lambek calculus. But they also suggest some natural extensions of the calculus, which are applied to the treatment of morphosyntactic dependencies and to an analysis of selectional restrictions. Finally, directed dependent function types are introduced, corresponding to the types of constructive type theory.Two alternative formalizations are given: one using syntax trees, like Montague grammar, and one dispensing with them, like the theory called minimalistic by Morrill. The syntax tree approach is presented as the main alternative, because it makes it possible to embed the calculus in a more extensive Montague-style grammar.     

Parsing of edNLC-graph grammars for scene analysis

An edNLC-graph grammar, introduced by Janssens,⁽⁴⁾ is a strong formalism for generating scene representations. This grammar generates directed node- and edge-labelled graphs, EDG-graphs. A method of construction of unambiguous string EDG-graph representation is briefly described. The characteristics of edNLC-graph grammar for syntactic pattern recognition allows us to construct the parsing algorithm. The deterministic top-down syntax analyzer is constructed for the subfamily of an edNLC-graph grammar, called an ETL/1-graph grammar. An ETL/1-graph grammar is parallel to a finite state string grammar. The notions introduced in the paper are useful for researches in less restricted edNLC-graph grammars, for example grammars analogical to context-free string grammars.     

Recursion Hypothesis Considered as a Research Program for Cognitive Science

Humans grasp discrete infinities within several cognitive domains, such as in language, thought, social cognition and tool-making. It is sometimes suggested that any such generative ability is based on a computational system processing hierarchical and recursive mental representations. One view concerning such generativity has been that each of the mind’s modules defining a cognitive domain implements its own recursive computational system. In this paper recent evidence to the contrary is reviewed and it is proposed that there is only one supramodal computational system with recursion in the human mind. A recursion thesis is defined, according to which the hominin cognitive evolution is constituted by a recent punctuated genetic mutation that installed the general, supramodal capacity for recursion into the human nervous system on top of the existing, evolutionarily older cognitive structures, and it is argued on the basis of empirical evidence and theoretical considerations that the recursion thesis constitutes a plausible research program for cognitive science.     

GLL parse-tree generation

Backtracking techniques which are often used to extend recursive descent (RD) parsers can have explosive run-times and cannot deal with grammars with left recursion. GLL parsers are fully general, worst-case cubic parsers which have the recursive descent-like property that they are easy to write and to use for grammar debugging. They have the direct relationship with the grammar that an RD parser has. In this paper we give an algorithm for generating GLL parsers which build an SPPF representation of the derivations of the input, complementing our existing GLL recognition algorithm, and we show that such parsers and recognisers are worst-case cubic.     

Syntactic word embedding based on dependency syntax and polysemous analysis

Most word embedding models have the following problems: (1) In the models based on bag-of-words contexts, the structural relations of sentences are completely neglected; (2) Each word uses a single embedding, which makes the model indiscriminative for polysemous words; (3) Word embedding easily tends to contextual structure similarity of sentences. To solve these problems, we propose an easy-to-use representation algorithm of syntactic word embedding (SWE). The main procedures are: (1) A polysemous tagging algorithm is used for polysemous representation by the latent Dirichlet allocation (LDA) algorithm; (2) Symbols ‘+’ and ‘?’ are adopted to indicate the directions of the dependency syntax; (3) Stopwords and their dependencies are deleted; (4) Dependency skip is applied to connect indirect dependencies; (5) Dependency-based contexts are inputted to a word2vec model. Experimental results show that our model generates desirable word embedding in similarity evaluation tasks. Besides, semantic and syntactic features can be captured from dependency-based syntactic contexts, exhibiting less topical and more syntactic similarity. We conclude that SWE outperforms single embedding learning models.     

Generation and synchronous tree-adjoining grammars

Tree-adjoining grammars (TAG) have been proposed as a formalism for generation based on the intuition that the extended domain of syntactic locality that TAGs provide should aid in localizing semantic dependencies as well, in turn serving as an aid to generation from semantic representations. We demonstrate that this intuition can be made concrete by using the formalism of synchronous tree-adjoining grammars. The use of synchronous TAGs for generation provides solutions to several problems with previous approaches to TAG generation. Furthermore, the semantic monotonicity requirement previously advocated for generation grammars as a computational aid is seen to be an inherent property of synchronous TAGs.     

文档检索中句法信息的有效利用研究

利用词项依存关系来改进词袋模型,一直是文本检索中一个热门话题。已有的定义词项依存的方法中,有两类主要的方法一类是词汇层次的依存关系,利用统计近邻信息来定义词项依存关系,另一类是句法层次的依存关系,由句法结构来定义词项依存关系。虽然已有的研究表明,相对于词袋模型,利用词项依存关系能够显著地提高检索性能,但这两类词项依存关系却缺乏系统的比较在利用词项依存关系来改进文档和查询的表达上,如何有效地利用句法信息,哪些句法信息对文本检索比较有效,依然是个有待研究的问题。为此,在文档表达上,比较了利用近邻信息和句法信息定义的词项依存关系的性能;在查询表达上,对利用不同层次的句法信息所定义的词项依存关系的性能进行了比较。为了系统地比较这些词项依存关系对检索性能的影响,在语言模型基础上,以平滑为思路,提出了一个能方便融入这两类词项依存关系的检索模型。在TREC语料上的实验表明,对于文档表达来说,句法关系较统计近邻关系没有明显的差别。在查询表达上,基于名词/专有词短语的部分句法信息较其他的句法信息更加有效。     

The Displacement Calculus

If all dependent expressions were adjacent some variety of immediate constituent analysis would suffice for grammar, but syntactic and semantic mismatches are characteristic of natural language; indeed this is a, or the, central problem in grammar. Logical categorial grammar reduces grammar to logic: an expression is well-formed if and only if an associated sequent is a theorem of a categorial logic. The paradigmatic categorial logic is the Lambek calculus, but being a logic of concatenation the Lambek calculus can only capture discontinuous dependencies when they are peripheral. In this paper we present the displacement calculus, which is a logic of intercalation as well as concatenation and which subsumes the Lambek calculus. On the empirical side, we apply the new calculus to discontinuous idioms, quantification, VP ellipsis, medial extraction, pied-piping, appositive relativisation, parentheticals, gapping, comparative subdeletion, cross-serial dependencies, reflexivization, anaphora, dative alternation, and particle shift. On the technical side, we prove that the calculus enjoys Cut-elimination.     

On the semantics of parsing actions

Parsers, whether constructed by hand or automatically via a parser generator tool, typically need to compute some useful semantic information in addition to the purely syntactic analysis of their input. Semantic actions may be added to parsing code by hand, or the parser generator may have its own syntax for annotating grammar rules with semantic actions. In this paper, we take a functional programming view of such actions. We use concepts from the semantics of mostly functional programming languages and adapt them to give meaning to the actions of the parser. Specifically, the semantics is inspired by the categorical semantics of lambda calculi and the use of premonoidal categories for the semantics of effects in programming languages. This framework is then applied to our leading example, the transformation of grammars to eliminate left recursion. The syntactic transformation of left-recursion elimination leads to a corresponding semantic transformation of the actions for the grammar. We prove the semantic transformation correct and relate it to continuation passing style, a widely studied transformation in lambda calculi and functional programming. As an idealization of the input language of parser generators, we define a call-by-value calculus with first-order functions and a type-and-effect system where the effects are given by sequences of grammar symbols. The account of left-recursion elimination is then extended to this calculus.     

基于词对依存分类的藏语树库半自动构建研究华

依据依存句法理论,该文制订了藏语句法标注体系及层次结构。通过分析构建藏语依存树库中存在的问题,提出了半自动依存树库构建模式,针对藏语特性提出了融合丰富特征的词对依存分类模型和依存边标注模型,实现了依存树库构建可视化工具,校对构建了1.1万句藏语依存句法树后,在基线系统下经实验验证,依存识别正确率提高了3%,使构建藏语依存树库工作取得了有效进展。     

Computer grammar of syntactic groups

A recognizing syntactic groups (SG) grammar, which corresponds to the formalism of systems of syntactic groups, is considered. The grammar was developed to describe the syntax of sentences in the natural language. The general criteria of separating out syntactic groups from a sequence of words, composing a text, and partial rules of the SG-grammar for the Russian and Ukrainian languages are described. Translated from Kibernetika i Sistemnyi Analiz, No. 6, pp. 166–176, November–December, 1999.     

A treatment of unbounded dependencies in eurotra with an experimental coindexation tool

The purpose of this article is to present a treatment of unbounded dependencies which is currently being experimented with in Eurotra. The treatment is based on the coindexation tool designed by the authors as an extension to the E-Framework, Eurotra's NLP formalism. At present, the tool has been tested in a systematic way in the Danish, French, Italian, and Spanish modules of the Eurotra translation system. Testing work on other languages (especially German) is in progress. Our article is organized as follows: in section 1, we discuss the linguistic and translational motivations for the treatment presented here; in section 2, we give the syntax and semantics of the two main components of the coindexation tool, namely the recursion markers and the copy operator; section 3 shows how this machinery can be applied for the implementation of unbounded dependency constructions according to our approach.

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Improving phrase-based statistical machine translation with morphosyntactic transformation

We present a phrase-based statistical machine translation approach which uses linguistic analysis in the preprocessing phase. The linguistic analysis includes morphological transformation and syntactic transformation. Since the word-order problem is solved using syntactic transformation, there is no reordering in the decoding phase. For morphological transformation, we use hand-crafted transformational rules. For syntactic transformation, we propose a transformational model based on a probabilistic context-free grammar. This model is trained using a bilingual corpus and a broad-coverage parser of the source language. This approach is applicable to language pairs in which the target language is poor in resources. We considered translation from English to Vietnamese and from English to French. Our experiments showed significant BLEU-score improvements in comparison with Pharaoh, a state-of-the-art phrase-based SMT system.     

基于句式结构的汉语图解析句法设计

梳理了汉语语法学界对“句式”这一术语的认识分歧;从中文信息处理角度分析了当前本领域句法分析和树库构建缺乏句式结构的现状;对黎氏语法形式化研究作了一个最新的综述,指出其在句式结构方面的优势和仍存在的不足;以黎氏语法图解法为原型改造设计出一种新型的汉语图解析句法,具体包括图形化的句法结构表示和结构化的XML存储格式。     

An efficient hierarchical identification method for general dual-rate sampled-data systems

For the lifted input–output representation of general dual-rate sampled-data systems, this paper presents a decomposition based recursive least squares (D-LS) identification algorithm using the hierarchical identification principle. Compared with the recursive least squares (RLS) algorithm, the proposed D-LS algorithm does not require computing the covariance matrices with large sizes and matrix inverses in each recursion step, and thus has a higher computational efficiency than the RLS algorithm. The performance analysis of the D-LS algorithm indicates that the parameter estimates can converge to their true values. A simulation example is given to confirm the convergence results.     

Recursion Isn’t Necessary for Human Language Processing: NEAR (Non-iterative Explicit Alternatives Rule) Grammars are Superior

Language sciences have long maintained a close and supposedly necessary coupling between the infinite productivity of the human language faculty and recursive grammars. Because of the formal equivalence between recursion and non-recursive iteration; recursion, in the technical sense, is never a necessary component of a generative grammar. Contrary to some assertions this equivalence extends to both center-embedded relative clauses and hierarchical parse trees. Inspection of language usage suggests that recursive rule components in fact contribute very little, and likely nothing significant, to linguistic creativity. Further than this, if the productivity of human language is considered as not rigidly bound, but not infinite, then the need for any sort of iteration in generative grammars vanishes and can be replaced with a Non-iterative Explicit Alternatives Rule grammar. The knock-on effects of dispensing with recursive (or any iterative) grammar components are: that language diversity can simply be based on rule and lexicon combinatorics with no potentially infinite dimensions derived from recursive or iterative components of rules; the oddity of a vast, multiply-infinite competence set of ‘grammatical but unacceptable’ productions is gone; and the development of a language faculty based on rules that eschew iterative rule components avoids any need for explaining ‘special’ mechanisms. On the broader front of searching for the mechanisms of mind, our analysis can be similarly applied to the proposals for a recursive basis for mind as an explanation for humanity’s great leap forward.