Encoding Lexicalized Tree Adjoining Grammars with a Nonmonotonic Inheritance Hierarchy

This paper shows how DATR, a widely used formal language for lexical knowledge representation, can be used to define an LTAG lexicon as an inheritance hierarchy with internal lexical rules. A bottom-up featural encoding is used for LTAG trees and this allows lexical rules to be implemented as covariation constraints within feature structures. Such an approach eliminates the considerable redundancy otherwise associated with an LTAG lexicon.Comment: Latex source, needs aclap.sty, 8 page

MODELING DEPONENCY IN GERMANIC PRETERITE-PRESENT VERBS USING DATR

In certain Germanic languages, there is a group of verbs called preterite-present verbs that are often viewed as irregular, but in fact behave very predictably. They exhibit a morphological phenomenon called deponency, often in conjunction with another morphological phenomenon called heteroclisis. I examine the preterite-present verbs of three different languages: Old Norse, Modern Icelandic, and Modern German. Initially, I approach them from a historical perspective and then seek to reconcile their morphology with the modern perspective. A criteria is established for a canonical preterite-present verb, and then using a lexical programming language called DATR, I create code that generates the appropriate paradigms while also illustrating the morphological relationships between verb tenses and inflection classes, among other things. DATR is a programming language used specifically for language models

INFERENTIAL-REALIZATIONAL MORPHOLOGY AND AFFIX ORDERING: EVIDENCE FROM THE AGREEMENT PATTERNS OF BASQUE AUXILIARY VERBS

“No aspect of Basque linguistics has received more attention over the years than the morphology of the verb.” (Trask 1981:1) The current study examines the complex morphological agreement patterns found in the Basque auxiliary verb system as a case in point for discussion of theoretical approaches to inflectional morphology. The traditional syntax-driven treatment of these auxiliaries is contrasted with an inferential, morphology-driven analysis within the Paradigm Function Morphology framework. Additionally, a computational implementation of the current analysis using the DATR lexical knowledge representation language is discussed

GENERATING AMHARIC PRESENT TENSE VERBS: A NETWORK MORPHOLOGY & DATR ACCOUNT

In this thesis I attempt to model, that is, computationally reproduce, the natural transmission (i.e. inflectional regularities) of twenty present tense Amharic verbs (i.e. triradicals beginning with consonants) as used by the language’s speakers. I root my approach in the linguistic theory of network morphology (NM) and model it using the DATR evaluator. In Chapter 1, I provide an overview of Amharic and discuss the fidel as an abugida, the verb system’s root-and-pattern morphology, and how radicals of each lexeme interacts with prefixes and suffixes. I offer an overview of NM in Chapter 2 and DATR in Chapter 3. In both chapters I draw attention to and help interpret key terms used among scholars doing work in both fields. In Chapter 4 I set forth my full theory, along with notation, for generating the paradigms of twenty present tense Amharic verbs that follow four different patterns. Chapter 5, the final chapter, contains a summary and offers several conclusions. I provide the DATR output in the Appendix. In writing, my main hope is that this project will make a contribution, however minimal or sizeable, that might advance the field of Amharic studies in particular and (computational) linguistics in general

Indexed Stems and Russian Word Formation: A Network Morphology Account of Russian Personal Nouns

Recent lexeme-based models have proposed that a lexeme carries an inventory of stems on which morphological rules operate. The various stems in the inventory are associated with different morphological rules, of both inflection and derivation. Furthermore, one stem may be selected by more than one rule. For this reason stems in the inventory are labeled with indexes, rather than being directly associated with a particular morphological function. It is claimed that an indexed-stem approach captures generalizations in the morphological system that would otherwise be missed. We argue that such an approach provides for greater generalization in the Russian morphological system. One area of Russian derivation that particularly lends itself to an indexed-stem approach is the highly productive system of personal-noun formation. We present a declarative account of Russian personal nouns that assumes indexed stems and show how such an account on the one hand obviates the need to posit either compound suffixes or concatenators and on the other dispenses with truncating/deleting rules. The account is couched within network morphology, a declarative lexeme-based framework that rests on the concept of default inheritance and is expressed in the computable lexical knowledge representation language D AT R

nPI Resummation in 3D SU(N) Higgs Theory

We test the utility of the nPI formalism for solving nonperturbative dynamics of gauge theories by applying it to study the phase diagram of SU(N) Higgs theory in 3 Euclidean spacetime dimensions. Solutions reveal standard signatures of a first order phase transition with a critical endpoint leading to a crossover regime, in qualitative agreement with lattice studies. The location of the critical endpoint, x sim 0.14 for SU(2) with a fundamental Higgs, is in rough but not tight quantitative agreement with the lattice. We end by commenting on the overall effectiveness and limitations of an nPI effective action based study. In particular, we have been unable to find an nPI gauge-fixing procedure which can simultaneously display the right phase structure and correctly handle the large-VEV Higgs region. We explain why doing so appears to be a serious challenge.Comment: 24 pages plus appendices, 8 figure

Feature-based lexicons : an example and a comparison to DATR

A FEATURE-BASED lexicon is especially sensible for natural language processing systems which are feature-based. Feature-based lexicons offer the advantages: (i) having a maximally transparent (empty) interface to feature-based grammars and processors; (ii) supplying exactly the EXPRESSIVE CAPABILITY exploited in these systems; and (iii) providing concise, transparent, and elegantspecification possibilities for various lexical relationships, including both inflection and derivation. The development of TYPED feature description languages allows the use of INHERITANCE in lexical description, and recent work explores the use of DEFAULT INHERITANCE as a means of easing lexical development. TDL is the implementation of a TYPE DESCRIPTION LANGUAGE based on HPSG feature logics. It is employed for both lexical and grammatical specification. As a lexical specification tool, it not only realizes these advantages, but it also separates a linguistic and a computational view of lexical contents and supplies a development environment for lexicon engineering. The most important competitor for feature-based lexical work is the very competent special purpose tool DATR, whose interface to feature-based systems is, however, inherently problematic. It is argued that feature-based systems (such as TDL) and DATR look compatible because of their common mathematical interpretation as graph description languages for directed graphs, but that this masks radically different modeling conventions for the graphs themselves. The development of TDL is continuing at the German Artificial Intelligence Center (Deutsches Forschungszentrum für Künstliche Intelligenz - DFKI) in the natural language understanding project DISCO