243 research outputs found
The Mayor\u27s Henchmen and Henchwomen, Both White and Colored : Edward H. Armstrong and the Politics of Race in Daytona Beach, 1900-1940
Writing about his early twentieth-century childhood in Daytona, the renowned theologian Howard Thurman related a story about his older cousin and idol. Thorton Smith. A semi-pro baseball player in his youth, Smith had established himself by the 1920s as a successful restaurateur in Midway, the most business-oriented of Daytona\u27s three black neighoorhoods. He purchased supplies from Edward Armstrong, a white grocer and aspiring politician who wanted to loosen the Ku Klux Klan\u27s grip on the city; Smith suggested to him that the Klan could be defeated only if blacks were allowed to vote. After in itially rejecting the idea, the grocer and his politicai allies finally agreed to grant the franchise to black property owners and taxpayers, and the biracial alliance eventually managed to unseat the Klan. After thanking Smith, Armstrong offered tile black businessman an envelope stuffed with cash, which Smith rejected. Instead, he demanded and received from the Armstrong faction a new school for black children and uniformed black policemen to patrol African American neighborhoods
Social Ranking Techniques for the Web
The proliferation of social media has the potential for changing the
structure and organization of the web. In the past, scientists have looked at
the web as a large connected component to understand how the topology of
hyperlinks correlates with the quality of information contained in the page and
they proposed techniques to rank information contained in web pages. We argue
that information from web pages and network data on social relationships can be
combined to create a personalized and socially connected web. In this paper, we
look at the web as a composition of two networks, one consisting of information
in web pages and the other of personal data shared on social media web sites.
Together, they allow us to analyze how social media tunnels the flow of
information from person to person and how to use the structure of the social
network to rank, deliver, and organize information specifically for each
individual user. We validate our social ranking concepts through a ranking
experiment conducted on web pages that users shared on Google Buzz and Twitter.Comment: 7 pages, ASONAM 201
Bidirectional PageRank Estimation: From Average-Case to Worst-Case
We present a new algorithm for estimating the Personalized PageRank (PPR)
between a source and target node on undirected graphs, with sublinear
running-time guarantees over the worst-case choice of source and target nodes.
Our work builds on a recent line of work on bidirectional estimators for PPR,
which obtained sublinear running-time guarantees but in an average-case sense,
for a uniformly random choice of target node. Crucially, we show how the
reversibility of random walks on undirected networks can be exploited to
convert average-case to worst-case guarantees. While past bidirectional methods
combine forward random walks with reverse local pushes, our algorithm combines
forward local pushes with reverse random walks. We also discuss how to modify
our methods to estimate random-walk probabilities for any length distribution,
thereby obtaining fast algorithms for estimating general graph diffusions,
including the heat kernel, on undirected networks.Comment: Workshop on Algorithms and Models for the Web-Graph (WAW) 201
A Statistical Measure of Complexity
A measure of complexity based on a probabilistic description of physical
systems is proposed. This measure incorporates the main features of the
intuitive notion of such a magnitude. It can be applied to many physical
situations and to different descriptions of a given system. Moreover, the
calculation of its value does not require a considerable computational effort
in many cases of physical interest.Comment: 8 pages, 0 figure
Factorization in Formal Languages
We consider several novel aspects of unique factorization in formal
languages. We reprove the familiar fact that the set uf(L) of words having
unique factorization into elements of L is regular if L is regular, and from
this deduce an quadratic upper and lower bound on the length of the shortest
word not in uf(L). We observe that uf(L) need not be context-free if L is
context-free.
Next, we consider variations on unique factorization. We define a notion of
"semi-unique" factorization, where every factorization has the same number of
terms, and show that, if L is regular or even finite, the set of words having
such a factorization need not be context-free. Finally, we consider additional
variations, such as unique factorization "up to permutation" and "up to
subset"
Patterns of Individual Shopping Behavior
Much of economic theory is built on observations of aggregate, rather than
individual, behavior. Here, we present novel findings on human shopping
patterns at the resolution of a single purchase. Our results suggest that much
of our seemingly elective activity is actually driven by simple routines. While
the interleaving of shopping events creates randomness at the small scale, on
the whole consumer behavior is largely predictable. We also examine
income-dependent differences in how people shop, and find that wealthy
individuals are more likely to bundle shopping trips. These results validate
previous work on mobility from cell phone data, while describing the
unpredictability of behavior at higher resolution.Comment: 4 pages, 5 figure
On the ground states of the Bernasconi model
The ground states of the Bernasconi model are binary +1/-1 sequences of
length N with low autocorrelations. We introduce the notion of perfect
sequences, binary sequences with one-valued off-peak correlations of minimum
amount. If they exist, they are ground states. Using results from the
mathematical theory of cyclic difference sets, we specify all values of N for
which perfect sequences do exist and how to construct them. For other values of
N, we investigate almost perfect sequences, i.e. sequences with two-valued
off-peak correlations of minimum amount. Numerical and analytical results
support the conjecture that almost perfect sequences do exist for all values of
N, but that they are not always ground states. We present a construction for
low-energy configurations that works if N is the product of two odd primes.Comment: 12 pages, LaTeX2e; extended content, added references; submitted to
J.Phys.
A method to discern complexity in two-dimensional patterns generated by coupled map lattices
Complex patterns generated by the time evolution of a one-dimensional
digitalized coupled map lattice are quantitatively analyzed. A method for
discerning complexity among the different patterns is implemented. The
quantitative results indicate two zones in parameter space where the dynamics
shows the most complex patterns. These zones are located on the two edges of an
absorbent region where the system displays spatio-temporal intermittency.Comment: 3 pages, 3 figures; some information about the authors:
http://add.unizar.es/public/100_16613/index.htm
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