Computational Morphological Analysis Research Articles

Insights into the pathogenesis of cerebral fusiform aneurysms: high-resolution MRI and computational analysis

BackgroundIntracranial fusiform aneurysms are complex and poorly characterized vascular lesions. High-resolution magnetic resonance imaging (HR-MRI) and computational morphological analysis may be used to characterize cerebral fusiform aneurysms.ObjectiveTo use advanced imaging...

A Computational Approach to Zulu Verb Morphology within the Context of Lexical Semantics

The central research question that is addressed in this article is: How can ZulMorph, a finite state morphological analyser for Zulu, be employed to add value to Zulu lexical semantics with specific reference to Zulu verbs? The verb is the most complex word category in Zulu. Due to the agglutinative nature of Zulu morphology, limited information can be computationally extracted from running Zulu text without the support of sufficiently reliable computational morphological analysis by means of which the essential meanings of, amongst others, verbs can be exposed. In this article we describe a corpus-based approach to adding the English meaning to Zulu extended verb roots, thereby enhancing ZulMorph as a lexical knowledge base.

Computational geometry-based scale space for edge-preserving multiscale image decomposition

Recently many computational photography applications need to decompose an image into a piecewise smooth base layer, containing large-scale variations in intensity, and a residual detail layer capturing the smaller-scale details in the image. In these applications, the image decomposition method requires multiscale ability to avoid visual artifacts. In this paper, we propose a new model of image decomposition that has the properties of edge-preserving and multiscale ability. Inspired by techniques in computational geometry and morphological image analysis, we use the α -scale space of the input image to extract information about oscillations. We define detail as oscillations between upper and lower envelope of the input image. Building on the key observation that the spatial scale of oscillations is characterized by the α value, we develop an algorithm for decomposing images into multiple scales of superposed oscillations. Compared with traditional image decomposition methods, our method has three advantages as follows: (1) precisely controls scale parameter; (2) preserves edge while decomposing; and (3) decouples noise layer from noisy image. Finally, we compare our results with current existing edge-preserving image decomposition algorithms and demonstrate applications.

Multiple object agreement morphemes in Setswana: A computational approach

Setswana is an agglutinative language where prefixes and suffixes are extensively used in the formation of words. Words such as verbs, pronouns, adjectives and so on, which have a grammatical relationship with nouns in sentences, demonstrate agreement with such nouns by means of agreement morphemes. In certain instances verbs in Setswana sentences may take two objects. Both of these objects may be represented in the verb by object agreement morphemes. The result is that two object agreement morphemes may be prefixed to the verb. While the morphemes of the verb are presented systematically in Setswana grammars, the occurrence of multiple object agreement morphemes has received limited attention in the literature on Setswana linguistics. Similarly, this phenomenon has not yet been investigated from a computational morphological point of view. This article reports on (i) an example-based investigation towards a better and more complete understanding of the phenomenon of multiple object agreement morphemes as they appear in Setswana verbs, (ii) the modelling of these morphemes in an existing finite state tokeniser and computational morphological analyser for Setswana, and (iii) the novel role that a morphological analyser and its guesser variant can play in a corpus-based investigation of the phenomenon under discussion.

Towards Zulu corpus clean-up, lexicon development and corpus annotation by means of computational morphological analysis

This article reports on a practical, semi-automated procedure towards creating a clean, morphologically annotated Zulu corpus of tractable size that could eventually serve both as a gold standard for Zulu computational morphology and as basis for further linguistic annotation. A corpus development architecture is proposed which includes the corpus in various stages of development, a pre-processing module, the Zulu morphological analyser and its guesser variant, the machine-readable lexicon that serves as comprehensive lexical database for Zulu, and a human elicitation function for ensuring the integrity of the lexical database. The approach is novel in the sense that an existing rule-based, finitestate Zulu computational morphological analyser is used as a core technology in this procedure to facilitate the complex, agglutinative nature of Zulu morphology. The corpus, at present consisting of the Zulu version of the South African Constitution, will have morphological analysis and tagging as a first level of annotation.

Lexical generality as a determinant of extension position in Northern Sotho

To date, no comprehensive study of verbal extension sequencing in Northern Sotho has been undertaken. This article is about verbal extension sequencing and emanates from research towards the building of a computational morphological analyser for Northern Sotho. It recognizes two theories about affix ordering, namely Hyman (2002) who argues in favour of a Pan-Bantu suffix template as the determinant of verbal extension order and Bybee (1985) who ascribes affix ordering to the semantic function and scope of affixes. The applicability of Hyman's Causative-Applied-Reciprocal-Passive (CARP) order to Northern Sotho verb stems is not doubted, but due to the nature of this study, the ordering of all other verbal extensions had to be investigated as well. The article seeks explanations for the ordering of verbal extensions in Northern Sotho by means of an analysis of verb stems taken from a sizeable portion of the Comprehensive Northern Sotho Dictionary (CNSD). Lexical generality (Bybee, 1985:16–17) is one of a range of criteria that are applied to determine whether affixes are inflectionally or derivationally inclined. It is used to determine the productivity of all verbal extensions of Northern Sotho that are listed against each of the 458 Northern Sotho verb stems in the CNSD selected for this study. The data shows a near direct correlation between the relative positions of verbal extensions and their productivity. The article confirms the link between two criteria for inflection as opposed to derivation for Northern Sotho, namely the criteria of generality and of proximity to the stem, as originally proposed by Bybee (1985). Further research is required to throw more light onto the question of whether or not extension ordering is determined by the morphology proper as proposed by Hyman (2002) or by morphology- external factors as proposed by Bybee (1985).

Improving the Computational Morphological Analysis of a Swahili Corpus for Lexicographic Purposes

Computational morphological analysis is an important first step in the automatic treatment of natural language and a useful lexicographic tool. This article describes a corpus-based approach to the morphological analysis of Swahili. We particularly focus our discussion on its ability to retrieve lemmas for word forms and evaluate it as a tool for corpus-based dictionary compilation. Keywords: LEXICOGRAPHY, MORPHOLOGY, CORPUS ANNOTATION, LEMMATIZATION, MACHINE LEARNING, SWAHILI (KISWAHILI)

Statistical Dynamics of Flowing Red Blood Cells by Morphological Image Processing

Blood is a dense suspension of soft non-Brownian cells of unique importance. Physiological blood flow involves complex interactions of blood cells with each other and with the environment due to the combined effects of varying cell concentration, cell morphology, cell rheology, and confinement. We analyze these interactions using computational morphological image analysis and machine learning algorithms to quantify the non-equilibrium fluctuations of cellular velocities in a minimal, quasi-two-dimensional microfluidic setting that enables high-resolution spatio-temporal measurements of blood cell flow. In particular, we measure the effective hydrodynamic diffusivity of blood cells and analyze its relationship to macroscopic properties such as bulk flow velocity and density. We also use the effective suspension temperature to distinguish the flow of normal red blood cells and pathological sickled red blood cells and suggest that this temperature may help to characterize the propensity for stasis in Virchow's Triad of blood clotting and thrombosis.

Containing overgeneration in Zulu computational morphology

The development of a large-coverage, computational morphological analyser for Zulu requires the modelling not only of the regular phenomena often associated with word formation, but also the idiosyncratic behaviour that may occur in Zulu morphology. This paper discusses the application of an existing rule-based, finite-state morphological analyser prototype ZulMorph in semi-automating the mining of available Zulu language corpora for idiosyncratic behaviour. The semi-automated procedure makes provision for bootstrapping the morphological analyser to include newly extracted information from corpora. Of particular interest is also the central role that the machine-readable lexicon plays. The procedure is applied to a Zulu development corpus of 30 000 types and the results are given and discussed.

Towards a computational morphological analysis of Setswana compounds

The development of a computational morphological analyser for Setswana necessitates the accurate modelling and implementation of, among others, compounding as a word formation process. Compounding is known to be an area of Setswana morphology that has sadly been neglected and still requires much investigation and research. The main purpose of this article is to investigate the formation of noun + noun compounds by computational morphological means in order to understand how this process should be formalised, modelled and subsequently implemented. In particular, an empirical study based on a collection of Setswana noun + noun compounds is reported on. The computational morphological analysis of these compounds revealed linguistic deviations from the standard morphological rules governing the formation of nouns and deverbatives. Examples, computational results and a discussion of the main findings are included.

Verbal extension sequencing: an examination from a computational perspective

Lexical transducers utilise a two-level finite-state network to simultaneously code morphological analysis and morphological generation rewrite rules. Multiple extensions following the verb root can be morphologically analysed as a closed morpheme class using different computational techniques. Analysis of a multiple extension sequence is achieved by trivial analysis, based on any combination of the closed class members, but this produces unnecessary over-generation of lexical items, many of which may not occur in a lexicon. Limiting the extension combinations, in an attempt to represent examples that may actually exist – in terms of both the possible number of extensions in a sequence and the relative ordering of the extensions – leads to a radical reduction in the generation of lexical items while the ability to analyse adequately is maintained. The article highlights details of an investigation based on both trivial analysis and an approach that prevents dramatic overgeneration. The article is based on test data reflecting possible extension sequences and the morphophonemic alternations of these extensions for Northern Sotho, garnered from literature research, lexicographic investigation and the computational morphological analysis of texts.

A computational morphological analyser for Northern Sotho deverbative nouns: applying Xerox finite-state software to traditional grammar

To create a computational morphological analyser, it is necessary to formalize both morphotactic (word formation) rules and morphophonemic (alternation) rules. This article describes the status of a morphological analyser for Northern Sotho deverbative nouns, based on rules extracted from the best available traditional grammars and implemented using Xerox finite-state technology. The rigor of creating a computational morphological analyser, and testing it on large corpora, has led to improvements in the rules themselves and in the understanding of the phenomena. The linguistic information is based on research involving prominent Northern Sotho grammars and tested against data from electronic written sources. It is highlighted that rigorous computational language formalism elicits interesting results linguistically as linguistic rules need to be re-examined more carefully and verified in practice.

A finite-state morphological analysis of Tswana nouns

This article describes the progress made in developing a broad-coverage computational morphological analyser for Tswana, an agglutinative disjunctively written indigenous South African language. Two central questions are addressed, viz. what is essential in order to build a broad-coverage computational morphological analyser/generator and how do we go about building this software application? In answer to the first question, a precise linguistic description is required of the linguistic phenomena mechanisms governing the morphology of the relevant natural language, in this case Tswana, the accurate modelling and implementation of these morphological phenomena and, ideally speaking, a complete list of all and only the valid roots and stems in Tswana. The answer to the second question lies within the realm of the discipline of software engineering and its methodologies. The article discusses the development of a morphological analyser with respect to the appropriate life cycle model, tools and testing procedures; Tswana noun morphology, in particular, the relevant morphotactics and morphophonological alternation rules; their modelling and implementation: preliminary results; testing procedures and future work.

AUTOMATED MORPHOMETRIC ANALYSIS OF THE CAT RETINAL α/Y, β/X AND δ GANGLION CELLS USING WAVELET STATISTICAL MOMENT AND CLUSTERING ALGORITHMS

Computational morphological analysis comprises the development of measures (indicators) that describe different form attributes of a neuron and provides additional parameters for classification algorithms. Our work addressed the problem of small group sizes often encountered in neuromorphological and neurophysiological research, automated classification tasks (unsupervised learning) and introduced a new morphological measure: the wavelet statistical moment. We analysed cat alpha/Y, beta/X and delta Golgi-stained retinal ganglion cells using six different shape features (circularity, 2(nd) statistical moment and entropy of Gaussian blurred images, wavelet statistical moment, number of terminations and the fractal dimension). This allowed us to compare the sensitivity of the methods in uniquely describing morphological attributes of these cells.

The significance of computational morphological for Zulu lexicography

With regard to the significance of computational morphological analysis for Zulu, and more specifically for Zulu lexicography, the aims of this article are the following: Firstly, we discuss computational morphological analysis as an enabling technology in the field of natural language processing (NLP) with specific reference to lexicography. Secondly, we explain how a computational morphological analyser for Zulu is built by using the Xerox finite-state tools. Thirdly, we demonstrate the application of such an analyser by means of examples from Zulu. Finally, we argue that in Zulu lexicography, a computational morphological analyser is an indispensable tool for facilitating some of the basic outputs of electronic corpora.