Fast Searching in Packed Strings

Given strings $P$ and $Q$ the (exact) string matching problem is to find all positions of substrings in $Q$ matching $P$. The classical Knuth-Morris-Pratt algorithm [SIAM J. Comput., 1977] solves the string matching problem in linear time which is optimal if we can only read one character at the time. However, most strings are stored in a computer in a packed representation with several characters in a single word, giving us the opportunity to read multiple characters simultaneously. In this paper we study the worst-case complexity of string matching on strings given in packed representation. Let $m \leq n$ be the lengths $P$ and $Q$, respectively, and let $\sigma$ denote the size of the alphabet. On a standard unit-cost word-RAM with logarithmic word size we present an algorithm using time O\left(\frac{n}{\log_\sigma n} + m + \occ\right). Here \occ is the number of occurrences of $P$ in $Q$. For $m = o(n)$ this improves the $O(n)$ bound of the Knuth-Morris-Pratt algorithm. Furthermore, if $m = O(n/\log_\sigma n)$ our algorithm is optimal since any algorithm must spend at least \Omega(\frac{(n+m)\log \sigma}{\log n} + \occ) = \Omega(\frac{n}{\log_\sigma n} + \occ) time to read the input and report all occurrences. The result is obtained by a novel automaton construction based on the Knuth-Morris-Pratt algorithm combined with a new compact representation of subautomata allowing an optimal tabulation-based simulation.Comment: To appear in Journal of Discrete Algorithms. Special Issue on CPM 200

Shaping a Corporate Identity From Below; the Role of the BAT Bulletin.

Existing studies that have explored the use of company journals as a mode of corporate communication during the early 20th century have invariably adopted an instrumentalist view of these publications. Company journals have been seen as a means of projecting to employees a top-down view of organisations. This article identifies a counter-example in which the origins of a company journal, the 'Bat Bulletin', are seen to arise as the result of an initiative stemming from the employees themselves. These antecedents gave the 'Bat Bulletin' a high degree of legitimacy amongst staff and provided the company with an important means of establishing a unified corporate culture across a disparate group international operating companies. Over time, however, the contents of the journal gradually became more conventional, and it was eventually closed down when the strategy of international integration ceased to be a desirable corporate objective during the 1930's

Faster Approximate String Matching for Short Patterns

We study the classical approximate string matching problem, that is, given strings $P$ and $Q$ and an error threshold $k$, find all ending positions of substrings of $Q$ whose edit distance to $P$ is at most $k$. Let $P$ and $Q$ have lengths $m$ and $n$, respectively. On a standard unit-cost word RAM with word size $w \geq \log n$ we present an algorithm using time $$O(nk \cdot \min(\frac{\log^2 m}{\log n},\frac{\log^2 m\log w}{w}) + n)$$ When $P$ is short, namely, $m = 2^{o(\sqrt{\log n})}$ or $m = 2^{o(\sqrt{w/\log w})}$ this improves the previously best known time bounds for the problem. The result is achieved using a novel implementation of the Landau-Vishkin algorithm based on tabulation and word-level parallelism.Comment: To appear in Theory of Computing System

Efficient exact pattern-matching in proteomic sequences

This paper proposes a novel algorithm for complete exact pattern-matching focusing the specificities of protein sequences (alphabet of 20 symbols) but, also highly efficient considering larger alphabets. The searching strategy uses large search windows allowing multiple alignments per iteration. A new filtering heuristic, named compatibility rule, contributed decisively to the efficiency improvement. The new algorithm’s performance is, on average, superior in comparison with its best-rated competitors

Finding a moral homeground: appropriately critical religious education and transmission of spiritual values

Values-inspired issues remain an important part of the British school curriculum. Avoiding moral relativism while fostering enthusiasm for spiritual values and applying them to non-curricular learning such as school ethos or children's home lives are challenges where spiritual, moral, social and cultural (SMSC) development might benefit from leadership by critical religious education (RE). Whether the school's model of spirituality is that of an individual spiritual tradition (schools of a particular religious character) or universal pluralistic religiosity (schools of plural religious character), the pedagogy of RE thought capable of leading SMSC development would be the dialogical approach with examples of successful implementation described by Gates, Ipgrave and Skeie. Marton's phenomenography, is thought to provide a valuable framework to allow the teacher to be appropriately critical in the transmission of spiritual values in schools of a particular religious character as evidenced by Hella's work in Lutheran schools

Active Brownian Particles. From Individual to Collective Stochastic Dynamics

We review theoretical models of individual motility as well as collective dynamics and pattern formation of active particles. We focus on simple models of active dynamics with a particular emphasis on nonlinear and stochastic dynamics of such self-propelled entities in the framework of statistical mechanics. Examples of such active units in complex physico-chemical and biological systems are chemically powered nano-rods, localized patterns in reaction-diffusion system, motile cells or macroscopic animals. Based on the description of individual motion of point-like active particles by stochastic differential equations, we discuss different velocity-dependent friction functions, the impact of various types of fluctuations and calculate characteristic observables such as stationary velocity distributions or diffusion coefficients. Finally, we consider not only the free and confined individual active dynamics but also different types of interaction between active particles. The resulting collective dynamical behavior of large assemblies and aggregates of active units is discussed and an overview over some recent results on spatiotemporal pattern formation in such systems is given.Comment: 161 pages, Review, Eur Phys J Special-Topics, accepte

Turkish information retrieval: Past changes future

One of the most exciting accomplishments of computer science in the lifetime of this generation is the World Wide Web. The Web is a global electronic publishing medium. Its size has been growing with an enormous speed for over a decade. Most of its content is objectionable, but it also contains a huge amount of valuable information. The Web adds a new dimension to the concept of information explosion and tries to solve the very same problem by information retrieval systems known as Web search engines. We briefly review the information explosion problem and information retrieval systems, convey the past and state of the art in Turkish information retrieval research, illustrate some recent developments, and propose some future actions in this research area in Turkey. © Springer-Verlag Berlin Heidelberg 2006

Relatório de estágio na Câmara Municipal de Ourém

O presente relatório enquadra-se no âmbito do trabalho final do curso Mestrado em Reabilitação Urbana, do Instituto Politécnico de Tomar. O estágio decorreu na Câmara Municipal de Ourém e teve como objeto, participar na coordenação com a Divisão Obras Municipais, Divisão da Ação Cultural e Divisão de Educação e Assuntos Sociais em intervenções a nível da Reabilitação Urbana. O estágio numa Câmara Municipal foi a opção que pareceu mais enriquecedora para conclusão do Mestrado em Reabilitação Urbana e para o futuro da minha vida profissional. Esta opção de estágio deve-se ao desejo de poder aplicar alguns dos conhecimentos obtidos ao longo do Mestrado, de conhecer a realidade do trabalho em obra e inserido numa equipa profissional, fiscalizadora, lidando com as responsabilidades inerentes à profissão. O relatório aborda quatro casos de estudo, respeitante às reabilitações, 1ª fase de intervenção na capela de São Sebastião em Atouguia, 2ª fase da reabilitação de zona de lazer no Agroal, freguesia de Formigais, 1ª fase de intervenção da capela da Perucha e reforço do pontão de Caxarias. Acompanhamento de pequenas reabilitações, reclamadas por juntas de freguesia e munícipes. O relatório procura descrever os procedimentos adotados no acompanhamento das obras de reabilitação e para fácil entendimento as descrições são acompanhadas por fotografias