(D+1)(D+1)-Colored Graphs - a Review of Sundry Properties

We review the combinatorial, topological, algebraic and metric properties supported by $(D+1)$-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