11,895 research outputs found
Key Distillation and the Secret-Bit Fraction
We consider distillation of secret bits from partially secret noisy
correlations P_ABE, shared between two honest parties and an eavesdropper. The
most studied distillation scenario consists of joint operations on a large
number of copies of the distribution (P_ABE)^N, assisted with public
communication. Here we consider distillation with only one copy of the
distribution, and instead of rates, the 'quality' of the distilled secret bits
is optimized, where the 'quality' is quantified by the secret-bit fraction of
the result. The secret-bit fraction of a binary distribution is the proportion
which constitutes a secret bit between Alice and Bob. With local operations and
public communication the maximal extractable secret-bit fraction from a
distribution P_ABE is found, and is denoted by Lambda[P_ABE]. This quantity is
shown to be nonincreasing under local operations and public communication, and
nondecreasing under eavesdropper's local operations: it is a secrecy monotone.
It is shown that if Lambda[P_ABE]>1/2 then P_ABE is distillable, thus providing
a sufficient condition for distillability. A simple expression for
Lambda[P_ABE] is found when the eavesdropper is decoupled, and when the honest
parties' information is binary and the local operations are reversible.
Intriguingly, for general distributions the (optimal) operation requires local
degradation of the data.Comment: 12 page
Hall-Littlewood polynomials and characters of affine Lie algebras
The Weyl-Kac character formula gives a beautiful closed-form expression for
the characters of integrable highest-weight modules of Kac-Moody algebras. It
is not, however, a formula that is combinatorial in nature, obscuring
positivity. In this paper we show that the theory of Hall-Littlewood
polynomials may be employed to prove Littlewood-type combinatorial formulas for
the characters of certain highest weight modules of the affine Lie algebras
C_n^{(1)}, A_{2n}^{(2)} and D_{n+1}^{(2)}. Through specialisation this yields
generalisations for B_n^{(1)}, C_n^{(1)}, A_{2n-1}^{(2)}, A_{2n}^{(2)} and
D_{n+1}^{(2)} of Macdonald's identities for powers of the Dedekind
eta-function. These generalised eta-function identities include the
Rogers-Ramanujan, Andrews-Gordon and G\"ollnitz-Gordon q-series as special,
low-rank cases.Comment: 33 pages, proofs of several conjectures from the earlier version have
been include
Expressing Privacy Preferences in terms of Invasiveness
Dynamic context aware systems need highly flexible privacy protection mechanisms. We describe an extension to an existing RBAC-based mechanism that utilises a dynamic measure of invasiveness to determine whether contextual information should be released
Evolutionary Inference for Function-valued Traits: Gaussian Process Regression on Phylogenies
Biological data objects often have both of the following features: (i) they
are functions rather than single numbers or vectors, and (ii) they are
correlated due to phylogenetic relationships. In this paper we give a flexible
statistical model for such data, by combining assumptions from phylogenetics
with Gaussian processes. We describe its use as a nonparametric Bayesian prior
distribution, both for prediction (placing posterior distributions on ancestral
functions) and model selection (comparing rates of evolution across a
phylogeny, or identifying the most likely phylogenies consistent with the
observed data). Our work is integrative, extending the popular phylogenetic
Brownian Motion and Ornstein-Uhlenbeck models to functional data and Bayesian
inference, and extending Gaussian Process regression to phylogenies. We provide
a brief illustration of the application of our method.Comment: 7 pages, 1 figur
Re-Politicising Regulation: Politics: Regulatory Variation and Fuzzy Liberalisation in the Single European Energy Market
[From the introduction] The idea that we are living in the age of the regulatory state has dominated the study of public policy in the European Union and its member states in general, and the study of the utilities sectors in particular.1 The European Commissionâs continuous drive to expand the Single Market has therefore been a free-market and rule-oriented project, driven by regulatory politics rather than policies that involve direct public expenditure. The dynamics of European integration are rooted in three central concepts: free trade, multilateral rules, and supranational cooperation. During the 1990s EU competition policy took a âpublic turnâ and set its sights on the public sector.2 EU legislation broke up national monopolies in telecommunications, electricity and gas, and set the scene for further extension of the single market into hitherto protected sectors. Both the integration theory literature (intergovernmentalist and institutionalist alike) and literature on the emergence of the EU as a âregulatory stateâ assumed that this was primarily a matter of policy making: once agreement had been reached to liberalise the utilities markets a relatively homogeneous process would follow. The regulatory state model fit the original common market blueprint better the old industrial policy approaches. On the other hand, sector-specific studies continue to reveal a less than fully homogeneous internal market. The EU has undergone momentous changes in the last two decades, which have rendered the notion of a homogeneous single market somewhat unrealistic
Highly comparative feature-based time-series classification
A highly comparative, feature-based approach to time series classification is
introduced that uses an extensive database of algorithms to extract thousands
of interpretable features from time series. These features are derived from
across the scientific time-series analysis literature, and include summaries of
time series in terms of their correlation structure, distribution, entropy,
stationarity, scaling properties, and fits to a range of time-series models.
After computing thousands of features for each time series in a training set,
those that are most informative of the class structure are selected using
greedy forward feature selection with a linear classifier. The resulting
feature-based classifiers automatically learn the differences between classes
using a reduced number of time-series properties, and circumvent the need to
calculate distances between time series. Representing time series in this way
results in orders of magnitude of dimensionality reduction, allowing the method
to perform well on very large datasets containing long time series or time
series of different lengths. For many of the datasets studied, classification
performance exceeded that of conventional instance-based classifiers, including
one nearest neighbor classifiers using Euclidean distances and dynamic time
warping and, most importantly, the features selected provide an understanding
of the properties of the dataset, insight that can guide further scientific
investigation
Alternative Archaeological Representations within Virtual Worlds
Traditional VR methods allow the user to tour and view the virtual world from different perspectives. Increasingly, more interactive and adaptive worlds are being generated, potentially allowing the user to interact with and affect objects in the virtual world. We describe and compare four models of operation that allow the publisher to generate views, with the client manipulating and affecting specific objects in the world. We demonstrate these approaches through a problem in archaeological visualization
- âŠ