20,426 research outputs found
-Colored Graphs - a Review of Sundry Properties
We review the combinatorial, topological, algebraic and metric properties
supported by -colored graphs, with a focus on those that are pertinent
to the study of tensor model theories. We show how to extract a limiting
continuum metric space from this set of graphs and detail properties of this
limit through the calculation of exponents at criticality
Agricultural Research and Poverty Alleviation: Some International Perspectives
Invited paper for the John L. Dillon AO Commemorative Day on ‘Agricultural Research: Challenges and Economics in the New Millenium’ The University of New England, Armidale NSW Australia, September 20, 2002Food Security and Poverty, Research and Development/Tech Change/Emerging Technologies,
Synthesis report of workshop on assessing the impact of policy-oriented social science research in Scheveningen, The Netherlands, November 12-13 2001
Economists have engaged for some time in developing methodologies for assessing the economic impact of agricultural research and in undertaking empirical studies to measure this impact. In recent years, they have documented more than 1,800 estimates of rates of return to agricultural research. Economists have paid little attention, however, to how to evaluate the impact of social science research. A symposium conducted by IFPRI in 1997 was one of the first attempts to address this knowledge gap. In November 2001, the Netherlands Ministry of Foreign Affairs and IFPRI brought together a group of researchers to follow up on the earlier symposium. Their conclusions fell into two broad categories: how to measure or value the economic impact of policy-oriented social science research and how to enhance the effectiveness of such research in policymaking environments. A number of lessons emerged from the workshop for donors, governments, and researchers about how to enhance the effectiveness of policy-oriented social science research....Because much remains to be learned about evaluating the impact of policy-oriented social science research, the workshop participants concluded that IFPRI should take the lead in developing a consortium to help improve interdisciplinary methods of assessing impact. The consortium would consist of institutions, donors, and individuals and would work in partnership with developing countries. Institutions could learn from each other about best practices and in the process exploit synergies, thereby increasing effectiveness and reducing the costs of what is an expensive undertaking.Agricultural research Economic aspects. ,Evaluation. ,Rate of return. ,Social sciences Research Evaluation. ,Research Economic aspects Congresses. ,
A Perspective on Unique Information: Directionality, Intuitions, and Secret Key Agreement
Recently, the partial information decomposition emerged as a promising
framework for identifying the meaningful components of the information
contained in a joint distribution. Its adoption and practical application,
however, have been stymied by the lack of a generally-accepted method of
quantifying its components. Here, we briefly discuss the bivariate (two-source)
partial information decomposition and two implicitly directional
interpretations used to intuitively motivate alternative component definitions.
Drawing parallels with secret key agreement rates from information-theoretic
cryptography, we demonstrate that these intuitions are mutually incompatible
and suggest that this underlies the persistence of competing definitions and
interpretations. Having highlighted this hitherto unacknowledged issue, we
outline several possible solutions.Comment: 5 pages, 3 tables;
http://csc.ucdavis.edu/~cmg/compmech/pubs/pid_intuition.ht
Unique Information via Dependency Constraints
The partial information decomposition (PID) is perhaps the leading proposal
for resolving information shared between a set of sources and a target into
redundant, synergistic, and unique constituents. Unfortunately, the PID
framework has been hindered by a lack of a generally agreed-upon, multivariate
method of quantifying the constituents. Here, we take a step toward rectifying
this by developing a decomposition based on a new method that quantifies unique
information. We first develop a broadly applicable method---the dependency
decomposition---that delineates how statistical dependencies influence the
structure of a joint distribution. The dependency decomposition then allows us
to define a measure of the information about a target that can be uniquely
attributed to a particular source as the least amount which the source-target
statistical dependency can influence the information shared between the sources
and the target. The result is the first measure that satisfies the core axioms
of the PID framework while not satisfying the Blackwell relation, which depends
on a particular interpretation of how the variables are related. This makes a
key step forward to a practical PID.Comment: 15 pages, 7 figures, 2 tables, 3 appendices;
http://csc.ucdavis.edu/~cmg/compmech/pubs/idep.ht
Capturing the phase diagram of (2+1)-dimensional CDT using a balls-in-boxes model
We study the phase diagram of a one-dimensional balls-in-boxes (BIB) model
that has been proposed as an effective model for the spatial-volume dynamics of
(2+1)-dimensional causal dynamical triangulations (CDT). The latter is a
statistical model of random geometries and a candidate for a nonperturbative
formulation of quantum gravity, and it is known to have an interesting phase
diagram, in particular including a phase of extended geometry with classical
properties. Our results corroborate a previous analysis suggesting that a
particular type of potential is needed in the BIB model in order to reproduce
the droplet condensation typical of the extended phase of CDT. Since such a
potential can be obtained by a minisuperspace reduction of a (2+1)-dimensional
gravity theory of the Ho\v{r}ava-Lifshitz type, our result strengthens the link
between CDT and Ho\v{r}ava-Lifshitz gravity.Comment: 21 pages, 7 figure
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