162,783 research outputs found
The horoboundary and isometry group of Thurston's Lipschitz metric
We show that the horofunction boundary of Teichm\"uller space with Thurston's
Lipschitz metric is the same as the Thurston boundary. We use this to determine
the isometry group of the Lipschitz metric, apart from in some exceptional
cases. We also show that the Teichm\"uller spaces of different surfaces, when
endowed with this metric, are not isometric, again with some possible
exceptions of low genus.Comment: 23 pages, 5 figures. There was a mistake in one of the lemmas. Fixing
it required replacing Lemmas 7.5, 7.6, and 7.7. The new version is very close
to the published versio
Data-Driven Reporting and Processing of Digital Archives with Brunnhilde
[Excerpt] Archivists are now several decades in to appraising, arranging, describing, preserving, and providing access to digital archives and have developed and adopted a number of tools to aid in specific tasks along the way. This article discusses Brunnhilde, a new tool developed to address one of the first steps in working with born-digital materials: characterizing the overall contents of directories or disks to enable smart evidence-based decision-making in the appraisal, arrangement, and description processes
A note on the consistency operator
It is a well known empirical observation that natural axiomatic theories are
pre-well-ordered by consistency strength. For any natural theory , the next
strongest natural theory is . We formulate and prove a
statement to the effect that the consistency operator is the weakest natural
way to uniformly extend axiomatic theories
An Empirical Study of the Manipulability of Single Transferable Voting
Voting is a simple mechanism to combine together the preferences of multiple
agents. Agents may try to manipulate the result of voting by mis-reporting
their preferences. One barrier that might exist to such manipulation is
computational complexity. In particular, it has been shown that it is NP-hard
to compute how to manipulate a number of different voting rules. However,
NP-hardness only bounds the worst-case complexity. Recent theoretical results
suggest that manipulation may often be easy in practice. In this paper, we
study empirically the manipulability of single transferable voting (STV) to
determine if computational complexity is really a barrier to manipulation. STV
was one of the first voting rules shown to be NP-hard. It also appears one of
the harder voting rules to manipulate. We sample a number of distributions of
votes including uniform and real world elections. In almost every election in
our experiments, it was easy to compute how a single agent could manipulate the
election or to prove that manipulation by a single agent was impossible.Comment: To appear in Proceedings of the 19th European Conference on
Artificial Intelligence (ECAI 2010
Semileptonic and Electroweak Penguin Results from BABAR
We report recent results from the BABAR experiment on semileptonic charmless
B-meson decays and electroweak penguin processes. Semileptonic charmless decays
are used to determine |Vub| and the exclusive modes considered here also begin
to constrain QCD-lattice form factor calculations. Radiative penguin decays are
both sensitive to physics beyond the Standard Model and can be used to extract
Heavy Quark parameters related to the b-quark mass and its motion inside the
hadron.Comment: To be submitted to the proceedings of the LVth Rencontres de Moriond
session devoted to "QCD and High Energy Hadronic Interactions", La
Thuile(Italy), 12-19th March 200
Symmetry Breaking Constraints: Recent Results
Symmetry is an important problem in many combinatorial problems. One way of
dealing with symmetry is to add constraints that eliminate symmetric solutions.
We survey recent results in this area, focusing especially on two common and
useful cases: symmetry breaking constraints for row and column symmetry, and
symmetry breaking constraints for eliminating value symmetryComment: To appear in Proceedings of Twenty-Sixth Conference on Artificial
Intelligence (AAAI-12
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