280 research outputs found
The Discrete Infinite Logistic Normal Distribution
We present the discrete infinite logistic normal distribution (DILN), a
Bayesian nonparametric prior for mixed membership models. DILN is a
generalization of the hierarchical Dirichlet process (HDP) that models
correlation structure between the weights of the atoms at the group level. We
derive a representation of DILN as a normalized collection of gamma-distributed
random variables, and study its statistical properties. We consider
applications to topic modeling and derive a variational inference algorithm for
approximate posterior inference. We study the empirical performance of the DILN
topic model on four corpora, comparing performance with the HDP and the
correlated topic model (CTM). To deal with large-scale data sets, we also
develop an online inference algorithm for DILN and compare with online HDP and
online LDA on the Nature magazine, which contains approximately 350,000
articles.Comment: This paper will appear in Bayesian Analysis. A shorter version of
this paper appeared at AISTATS 2011, Fort Lauderdale, FL, US
An Algorithm for Evolving Protocol Constraints
Centre for Intelligent Systems and their ApplicationsWe present an investigation into the design of an evolutionary mechanism for multiagent
protocol constraint optimisation. Starting with a review of common population
based mechanisms we discuss the properties of the mechanisms used by these search
methods. We derive a novel algorithm for optimisation of vectors of real numbers and
empirically validate the efficacy of the design by comparing against well known results
from the literature. We discuss the application of an optimiser to a novel problem
and remark upon the relevance of the no free lunch theorem. We show the relative
performance of the optimiser is strong and publish details of a new best result for the
Keane optimisation problem. We apply the final algorithm to the multi-agent protocol
optimisation problem and show the design process was successful
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