Research Articles (Mathematical Sciences)


Recent Submissions

  • Computational and theoretical analysis of human diseases associated with infectious pathogens 

    Noutchie, Suares Clovis Oukouomi; Kwuimy, Cedrick Aurelien Kitio; Tewa, Jean Jules; Nyabadza, Farai; Bildik, Necdet (Hindawi, 2015)
    Mathematical models and computer simulations are useful experimental tools for building and testing theories, assessing quantitative conjectures, answering specific questions, determining sensitivities to changes in parameter ...

  • On the validity of evolutionary models with site-specific parameters 

    Scheffler, Konrad; Murrell, Ben; Pond, Sergei L. Kosakovsky (PLoS, 2014-04-10)
    Evolutionary models that make use of site-specific parameters have recently been criticized on the grounds that parameter estimates obtained under such models can be unreliable and lack theoretical guarantees of convergence. ...

  • Spatial assortment of mixed propagules explains the acceleration of range expansion 

    Ramanantoanina, Andriamihaja; Ouhinou, Aziz; Hui, Cang (Public Library of Science, 2014-08)
    Abstract Range expansion of spreading organisms has been found to follow three types: (i) linear expansion with a constant rate of spread; (ii) bi-phase expansion with a faster linear expansion following a slower linear ...

  • Model checking rational agents 

    Bordini, Rafael H.; Fisher, Michael; Wooldridge, Michael; Visser, Willem (IEEE - -Institute of Electrical and Electronics Engineers, 2004-10)
    Agent-oriented programming techniques seem appropriate for developing systems that operate in complex, dynamic, and unpredictable environments. We aim to address this requirement by developing model-checking techniques for ...

  • Property-based slicing for agent verification 

    Bordini, Rafael H.; Fisher, Michael; Wooldridge, Michael; Visser, Willem (Oxford University Press (OUP), 2009-12)
    Programming languages designed specifically for multi-agent systems represent a new programming paradigm that has gained popularity over recent years, with some multi-agent programming languages being used in increasingly ...

  • A survey of new trends in symbolic execution for software testing and analysis 

    Pasareanu, Corina S.; Visser, Willem (Springer Verlag, 2009-10)
    Symbolic execution is a well-known program analysis technique which represents program inputs with symbolic values instead of concrete, initialized, data and executes the program by manipulating program expressions involving ...

  • Left ventricular segmentation from MRI datasets with edge modelling conditional random fields 

    Dreijer, Janto F.; Herbst, Ben M.; Du Preez, Johan A. (BioMed Central, 2013-07)
    Background: This paper considers automatic segmentation of the left cardiac ventricle in short axis magnetic resonance images. Various aspects, such as the presence of papillary muscles near the endocardium border, makes ...

  • Non-Negative Matrix Factorization for Learning Alignment-Specific Models of Protein Evolution 

    Murrell, Ben; Weighill, Thomas; Buys, Jan; Ketteringham, Robert; Moola, Sasha; Benade, Gerdus; du Buisson, Lise; Kaliski, Daniel; Hands, Tristan; Scheffler, Konrad (PLOS, 2011-12-22)
    Models of protein evolution currently come in two flavors: generalist and specialist. Generalist models (e.g. PAM, JTT, WAG) adopt a one-size-fits-all approach, where a single model is estimated from a number of different ...

  • Codon test : modeling amino acid substitution preferences in coding sequences 

    Delport, Wayne; Scheffler, Konrad; Botha, Gordon; Gravenor, Mike B.; Muse, Spencer V.; Pond, Sergei L. Kosakovsky (PLOS Computational Biology, 2010-08)
    Codon models of evolution have facilitated the interpretation of selective forces operating on genomes. These models, however, assume a single rate of non-synonymous substitution irrespective of the nature of amino acids ...

  • Modeling HIV-1 drug resistance as episodic directional selection 

    Murrell, Ben; De Oliveira, Tulio; Seebregts, Chris; Pond, Sergei L. Kosakovsky; Scheffler, Konrad (PLOS Computational Biology, 2011-05)
    The evolution of substitutions conferring drug resistance to HIV-1 is both episodic, occurring when patients are on antiretroviral therapy, and strongly directional, with site-specific resistant residues increasing in ...

  • Correcting the bias of empirical frequency parameter estimators in codon models 

    Kosakovsky Pond, Sergei; Delport, Wayne; Muse, Spencer V.; Scheffler, Konrad (Public Library of Science -- PLOS, 2010-07)
    Markov models of codon substitution are powerful inferential tools for studying biological processes such as natural selection and preferences in amino acid substitution. The equilibrium character distributions of these ...

  • The geometry of unitary 2-representations of finite groups and their 2-characters 

    Bartlett, Bruce (Springer Link, 2011-02)
    Motivated by topological quantum field theory, we investigate the geometric aspects of unitary 2-representations of finite groups on 2-Hilbert spaces, and their 2-characters. We show how the basic ideas of geometric ...

  • Francis Guthrie : a colourful life 

    Maritz, Pieter; Mouton, Sonja (Springer, 2012-09)
    In 1852, in London, Francis Guthrie posed the question of colouring a map with four colours only, the question that eventually became known as the Four Colour Problem. The problem is famous, but what else do we know of ...

  • Realization of abstract convex geometries by point configurations 

    Adaricheva, Kira; Wild, Marcel (Elsevier, 2010-01)
    The Edelman-Jamison problem is to characterize those abstract convex geometries that are representable by a set of points in the plane. We show that some natural modification of the Edelman-Jamison problem is equivalent ...

  • The asymptotic number of binary codes and binary matroids 

    Wild, Marcel (Society for Industrial and Applied Mathematics (SIAM), 2006-08)
    The asymptotic number of nonequivalent binary n-codes is determined. This is also the asymptotic number of nonisomorphic binary matroids on n elements.

  • Die Suid-Afrikaanse uitgebreide maritieme gebied : ’n alternatiewe metode vir die bepaling van die voet van die kontinentale helling 

    Pantland, N. A.; Van Vuuren, J. H. (AOSIS OpenJournal, 2006)
    Kuslande het ’n eenmalige geleentheid om by die Verenigde Nasies (VN) aansoek te doen om ’n uitgebreide maritieme gebied, indien hul wetenskaplik kan toon dat die voet van die kontinentale helling (VKH) buite hul soewereine ...

  • Decomposing the hypercube Qn into n isomorphic edge-disjoint trees 

    Wagner, Stephan; Wild, Marcel (Elsevier, 2012-02)
    The problem of finding edge-disjoint trees in a hypercube arises for example in the context of parallel computing [3]. Independently of applications it is of high aesthetic appeal. The hypercube of dimension n, denoted ...

  • Computing various types of lattices freely generated by posets 

    Wild, Marcel (Edizioni CERFIM Centro di Ricerche in Fisica e MatematicaResearch Center for Mathematics and Physics - Locarno - Switzerland, 2000)
    see item for abstract

  • Special subvarieties of Drinfeld modular varieties 

    Breuer, Florian (Walter de Gruyter, 2010-11)
    We explore an analogue of the Andr´e-Oort conjecture for subvarieties of Drinfeld modular varieties. The conjecture states that a subvariety X of a Drinfeld modular variety contains a Zariski-dense set of complex ...

  • Partitioning the hypercube Qn into n isomorphic edge-disjoint trees 

    Wagner, Stephan; Wild, Marcel (TU Graz University of Technology, 2011)
    ENGLISH ABSTRACT: The problem of finding edge-disjoint trees in a hypercube e.g. arises in the context of parallel computing. Independent of applications it is of high aesthetic appeal.

  • Computing the output distribution of a stack filter from the DNF of its positive Boolean function 

    Wild, Marcel (Cornell University Library, 2010)
    ENGLISH ABSTRACT: The majority of nonlinear filters used in practise are stack filters. An algorithm is presented which calculates the output distribution of an arbitrary stack filter S from the disjunctive normal form ...

  • Calculating the output distribution of stack filters that are erosion-dilation cascades, in particular LULU-filters 

    Anguelov, R.; Butler, P. W.; Rohwer, C. H.; Wild, Marcel (Cornell University Library, 2011)
    ENGLISH ABSTRACT: Two procedures to compute the output distribution 0S of certain stack filters S (so called erosion-dilation cascades) are given. One rests on the disjunctive normal form of S and also yields the rank ...

  • Compactly generating all satisfying truth assignments of a horn formula 

    Wild, Marcel (Delft University in cooperation with IOS Press, 2012-01)
    ENGLISH ABSTRACT: While it was known that all models of a Horn formula can be generated in outputpolynomial time, here we present an explicit algorithm as opposed to the rather vague oracle-scheme suggested in the proof ...