913 research outputs found
Complex Beauty
Complex systems and their underlying convoluted networks are ubiquitous, all
we need is an eye for them. They pose problems of organized complexity which
cannot be approached with a reductionist method. Complexity science and its
emergent sister network science both come to grips with the inherent complexity
of complex systems with an holistic strategy. The relevance of complexity,
however, transcends the sciences. Complex systems and networks are the focal
point of a philosophical, cultural and artistic turn of our tightly
interrelated and interdependent postmodern society. Here I take a different,
aesthetic perspective on complexity. I argue that complex systems can be
beautiful and can the object of artification - the neologism refers to
processes in which something that is not regarded as art in the traditional
sense of the word is changed into art. Complex systems and networks are
powerful sources of inspiration for the generative designer, for the artful
data visualizer, as well as for the traditional artist. I finally discuss the
benefits of a cross-fertilization between science and art
The skewness of computer science
Computer science is a relatively young discipline combining science,
engineering, and mathematics. The main flavors of computer science research
involve the theoretical development of conceptual models for the different
aspects of computing and the more applicative building of software artifacts
and assessment of their properties. In the computer science publication
culture, conferences are an important vehicle to quickly move ideas, and
journals often publish deeper versions of papers already presented at
conferences. These peculiarities of the discipline make computer science an
original research field within the sciences, and, therefore, the assessment of
classical bibliometric laws is particularly important for this field. In this
paper, we study the skewness of the distribution of citations to papers
published in computer science publication venues (journals and conferences). We
find that the skewness in the distribution of mean citedness of different
venues combines with the asymmetry in citedness of articles in each venue,
resulting in a highly asymmetric citation distribution with a power law tail.
Furthermore, the skewness of conference publications is more pronounced than
the asymmetry of journal papers. Finally, the impact of journal papers, as
measured with bibliometric indicators, largely dominates that of proceeding
papers.Comment: I applied the goodness-of-fit methodology proposed in: A. Clauset, C.
R. Shalizi, M. E. J. Newman. Power-law distributions in empirical data. SIAM
Review 51, 661-703 (2009
PageRank: Standing on the shoulders of giants
PageRank is a Web page ranking technique that has been a fundamental
ingredient in the development and success of the Google search engine. The
method is still one of the many signals that Google uses to determine which
pages are most important. The main idea behind PageRank is to determine the
importance of a Web page in terms of the importance assigned to the pages
hyperlinking to it. In fact, this thesis is not new, and has been previously
successfully exploited in different contexts. We review the PageRank method and
link it to some renowned previous techniques that we have found in the fields
of Web information retrieval, bibliometrics, sociometry, and econometrics
Temporalized logics and automata for time granularity
Suitable extensions of the monadic second-order theory of k successors have
been proposed in the literature to capture the notion of time granularity. In
this paper, we provide the monadic second-order theories of downward unbounded
layered structures, which are infinitely refinable structures consisting of a
coarsest domain and an infinite number of finer and finer domains, and of
upward unbounded layered structures, which consist of a finest domain and an
infinite number of coarser and coarser domains, with expressively complete and
elementarily decidable temporal logic counterparts.
We obtain such a result in two steps. First, we define a new class of
combined automata, called temporalized automata, which can be proved to be the
automata-theoretic counterpart of temporalized logics, and show that relevant
properties, such as closure under Boolean operations, decidability, and
expressive equivalence with respect to temporal logics, transfer from component
automata to temporalized ones. Then, we exploit the correspondence between
temporalized logics and automata to reduce the task of finding the temporal
logic counterparts of the given theories of time granularity to the easier one
of finding temporalized automata counterparts of them.Comment: Journal: Theory and Practice of Logic Programming Journal Acronym:
TPLP Category: Paper for Special Issue (Verification and Computational Logic)
Submitted: 18 March 2002, revised: 14 Januari 2003, accepted: 5 September
200
A theory on power in networks
The eigenvector centrality equation is a successful
compromise between simplicity and expressivity. It claims that central actors
are those connected with central others. For at least 70 years, this equation
has been explored in disparate contexts, including econometrics, sociometry,
bibliometrics, Web information retrieval, and network science. We propose an
equally elegant counterpart: the power equation , where
is the vector whose entries are the reciprocal of those of . It
asserts that power is in the hands of those connected with powerless others. It
is meaningful, for instance, in bargaining situations, where it is advantageous
to be connected to those who have few options. We tell the parallel, mostly
unexplored story of this intriguing equation
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