Derrick G. Kourie

AddIntent: A New Incremental Algorithm for Constructing Concept Lattices

An incremental concept lattice construction algorithm, called AddIntent, is proposed. In experimental comparison, AddIntent outperformed a selection of other published algorithms for most types of contexts and was close to the most efficient algorithm in other cases. The current best estimate for the algorithm’s upper bound complexity to construct a concept lattice L whose context has a set of objects G, each of which possesses at most max(|g′|) attributes, is O(|L||G|2 max(|g′|)).

Towards concise representation for taxonomies of epistemic communities

We present an application of formal concept analysis aimed at representing a meaningful structure of knowledge communities in the form of a lattice-based taxonomy. The taxonomy groups together agents (community members) who interact and/or develop a set of notions--i.e. cognitive properties of group members. In the absence of appropriate constraints on how it is built, a knowledge community taxonomy is in danger of becoming extremely complex, and thus difficult to comprehend. We consider two approaches to building a concise representation that respects the underlying structural relationships, while hiding uninteresting and/or superfluous information. The first is a pruning strategy that is based on the notion of concept stability, and the second is a representational improvement based on nested line diagrams. We illustrate the method with a small sample of a community of embryologists.

Software testing using model programs

A strategy described as ‘testing using M model programs’ (abbreviated to ‘M‐mp testing’) is investigated as a practical alternative to software testing based on manual outcome prediction. A model program implements suitably selected parts of the functional specification of the software to be tested. The M‐mp testing strategy requires that M (M ≥ 1) model programs as well as the program under test, P, should be independently developed. P and the M model programs are then subjected to the same test data. Difference analysis is conducted on the outputs and appropriate corrective action is taken. P and the M model programs jointly constitute an approximate test oracle. Both M‐mp testing and manual outcome prediction are subject to the possibility of correlated failure. In general, the suitability of M‐mp testing in a given context will depend on whether building and maintaining model programs is likely to be more cost effective than manually pre‐calculating Ps expected outcomes for given test data. In many contexts, M‐mp testing could also facilitate the attainment of higher test adequacy levels than would be possible with manual outcome prediction.

An incremental algorithm to construct a lattice of set intersections

An incremental algorithm to construct a lattice from a collection of sets is derived, refined, analyzed, and related to a similar previously published algorithm for constructing concept lattices. The lattice constructed by the algorithm is the one obtained by closing the collection of sets with respect to set intersection. The analysis explains the empirical efficiency of the related concept lattice construction algorithm that had been observed in previous studies. The derivation highlights the effectiveness of a correctness-by-construction approach to algorithm development.

Server-centric Web frameworks: An overview

Most contemporary Web frameworks may be classified as server-centric. An overview of such Web frameworks is presented. It is based on information gleaned from surveying 80 server-centric Web frameworks, as well as from popular related specifications. Requirements typically expected of a server-centric Web framework are discussed. Two Web framework taxonomies are proposed, reflecting two orthogonal ways of characterizing a framework: the way in which the markup language content of a browser-destined document is specified in the framework (presentation concerns); and the frameworks facilities for the user to control the flow of events between browser and server (control concerns).

A service oriented architecture for wireless sensor and actor network applications

The emergence of Wireless Sensor and Actor Networks (WSAN) has contributed significantly to the progress of ubiquitous and pervasive computing, but has also introduced new challenges. The authors researched this technology and its applicability to real-world scenarios through the Cerberus project. This paper offers a discussion of the processes the authors went through from initial contact with the technology to implementing a system based on it, as well as the problems faced while working with WSAN. These experiences indicate the need for a dynamic, mote and application-independent management system. A service oriented architecture (SOA) for the management of WSAN, which makes use of OSGi, is proposed and evaluated. This SOA allows for the updating and changing of the application largely independent of the mote configuration as well as for easy management of different types of motes and actors.

Building access control models with attribute exploration

The use of lattice-based access control models has been somewhat restricted by their complexity. We argue that attribute exploration from formal concept analysis can help create lattice models of manageable size, while making it possible for the system designer to better understand dependencies between different security categories in the domain and, thus, providing certain guarantees for the relevance of the constructed model to a particular application. In this paper, we introduce the method through an example.

Assessment of a framework to compare software development methodologies

A decision-supporting framework was applied in a pilot study to assist in the decision making about what software development methodology to use at a software engineering company. This paper critically assesses this decision making process and framework that was used at that company to decide on an appropriate software methodology for the analysis and design of business processes and software systems.

Mapping uniquely occurring short sequences derived from high throughput technologies to a reference genome

Novel high throughput sequencing technology methods have redefined the way genome sequencing is performed. They are able to produce tens of millions of short sequences (reads) in a single experiment and with a much lower cost than previous sequencing methods. Due to this massive amount of data generated by the above systems, efficient algorithms for mapping short sequences to a reference genome are in great demand. In this paper, we present a practical algorithm for addressing the problem of efficiently mapping uniquely occuring short reads to a reference genome. This requires the classification of these short reads into unique and duplicate matches. In particular, we define and solve the Massive Exact Unique Pattern Matching problem in genomes.

Lattices in machine learning: Complexity issues

Abstract. The use of a so-called concept lattice for deriving concepts from a given set of entities and attributes is examined. A number of variations are discussed including constrained, unconstrained and augmented concept lattices. Bounds for worst case behaviour, as well as conditions under which worst-case behaviour arises, are adduced. It is argued that worst-case behaviour is unlikely to arise in applications which are amenable to machine learning. Pruning is also mentioned as a means of keeping the lattice down to a tractable size.