59 research outputs found
Evolutionary Games and Computer Simulations
The prisoner's dilemma has long been considered the paradigm for studying the
emergence of cooperation among selfish individuals. Because of its importance,
it has been studied through computer experiments as well as in the laboratory
and by analytical means. However, there are important differences between the
way a system composed of many interacting elements is simulated by a digital
machine and the manner in which it behaves when studied in real experiments. In
some instances, these disparities can be marked enough so as to cast doubt on
the implications of cellular automata type simulations for the study of
cooperation in social systems. In particular, if such a simulation imposes
space-time granularity, then its ability to describe the real world may be
compromised. Indeed, we show that the results of digital simulations regarding
territoriality and cooperation differ greatly when time is discrete as opposed
to continuous.Comment: 8 pages. Also available through anonymous ftp from parcftp.xerox.com
in the directory /pub/dynamics as pdilemma.p
Training and Turnover in Organizations
We present a two-level model of organizational training and agent production.
Managers decide whether or not to train based on both the costs of training
compared to the benefits and on their expectations and observations of the
number of other firms that also train. Managers also take into account the sum
of their employees' contributions and the average tenure length within their
organization. Employees decide whether or not to contribute to production based
on their expectations as to how other employees will act. Trained workers learn
over time and fold their increased productivity into their decision whether or
not to contribute. We find that the dynamical behavior at the two levels is
closely coupled: the evolution of the industry over time depends not only on
the characteristics of training programs, learning curves, and cost-benefit
analyses, but on the vagaries of chance as well. For example, in one case, the
double dilemma can be resolved for the industry as a whole and productivity
then increases steadily over time. In another, the organizational level dilemma
may remain unresolved and workers may contribute at fluctuating levels. In this
case the overall productivity stays low. We also find a correlation between
high productivity and low turnover and show that a small increase in training
rates can lead to explosive growth in productivity.Comment: 9 pages. Also available through anonymous ftp from parcftp.xerox.com
in the directory pub/dynamics as training.p
Cascading Behavior in Large Blog Graphs
How do blogs cite and influence each other? How do such links evolve? Does
the popularity of old blog posts drop exponentially with time? These are some
of the questions that we address in this work. Our goal is to build a model
that generates realistic cascades, so that it can help us with link prediction
and outlier detection.
Blogs (weblogs) have become an important medium of information because of
their timely publication, ease of use, and wide availability. In fact, they
often make headlines, by discussing and discovering evidence about political
events and facts. Often blogs link to one another, creating a publicly
available record of how information and influence spreads through an underlying
social network. Aggregating links from several blog posts creates a directed
graph which we analyze to discover the patterns of information propagation in
blogspace, and thereby understand the underlying social network. Not only are
blogs interesting on their own merit, but our analysis also sheds light on how
rumors, viruses, and ideas propagate over social and computer networks.
Here we report some surprising findings of the blog linking and information
propagation structure, after we analyzed one of the largest available datasets,
with 45,000 blogs and ~ 2.2 million blog-postings. Our analysis also sheds
light on how rumors, viruses, and ideas propagate over social and computer
networks. We also present a simple model that mimics the spread of information
on the blogosphere, and produces information cascades very similar to those
found in real life
Leave a Reply: An Analysis of Weblog Comments
Access to weblogs, both through commercial services and in academic studies, is usually limited to the content of the weblog posts. This overlooks an important aspect distinguishing weblogs from other web pages: the ability of weblog readers to respond to posts directly, by posting comments. In this paper we present a large-scale study of weblog comments and their relation to the posts. Using a sizable corpus of comments, we estimate the overall volume of comments in the blogosphere; analyze the relation between the weblog popularity and commenting patterns in it; and measure the contribution of comment content to various aspects of weblog access
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