948 research outputs found
Instability of defensive alliances in the predator-prey model on complex networks
A model of six-species food web is studied in the viewpoint of spatial
interaction structures. Each species has two predators and two preys, and it
was previously known that the defensive alliances of three cyclically predating
species self-organize in two-dimensions. The alliance-breaking transition
occurs as either the mutation rate is increased or interaction topology is
randomized in the scheme of the Watts-Strogatz model. In the former case of
temporal disorder, via the finite-size scaling analysis the transition is
clearly shown to belong to the two-dimensional Ising universality class. In
contrast, the geometric or spatial randomness for the latter case yields a
discontinuous phase transition. The mean-field limit of the model is
analytically solved and then compared with numerical results. The dynamic
universality and the temporally periodic behaviors are also discussed.Comment: 5 page
Online Hyperparameter Meta-Learning with Hypergradient Distillation
Many gradient-based meta-learning methods assume a set of parameters that do
not participate in inner-optimization, which can be considered as
hyperparameters. Although such hyperparameters can be optimized using the
existing gradient-based hyperparameter optimization (HO) methods, they suffer
from the following issues. Unrolled differentiation methods do not scale well
to high-dimensional hyperparameters or horizon length, Implicit Function
Theorem (IFT) based methods are restrictive for online optimization, and short
horizon approximations suffer from short horizon bias. In this work, we propose
a novel HO method that can overcome these limitations, by approximating the
second-order term with knowledge distillation. Specifically, we parameterize a
single Jacobian-vector product (JVP) for each HO step and minimize the distance
from the true second-order term. Our method allows online optimization and also
is scalable to the hyperparameter dimension and the horizon length. We
demonstrate the effectiveness of our method on two different meta-learning
methods and three benchmark datasets
Research on Linked Data and Co-reference Resolution
This project report details work carried out in collaboration between the University of Southampton and the Korea Institute of Science and Technology Information, focussing on an RDF dataset of academic authors and publications. Activities included the conversion of the dataset to produce Linked Data, the identification of co-references in and between datasets, and the development of an ontology mapping service to facilitate the integration of the dataset with an existing Semantic Web application, RKBExplorer.com
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