2,756 research outputs found
Logic Programs with Compiled Preferences
We describe an approach for compiling preferences into logic programs under
the answer set semantics. An ordered logic program is an extended logic program
in which rules are named by unique terms, and in which preferences among rules
are given by a set of dedicated atoms. An ordered logic program is transformed
into a second, regular, extended logic program wherein the preferences are
respected, in that the answer sets obtained in the transformed theory
correspond with the preferred answer sets of the original theory. Our approach
allows both the specification of static orderings (as found in most previous
work), in which preferences are external to a logic program, as well as
orderings on sets of rules. In large part then, we are interested in describing
a general methodology for uniformly incorporating preference information in a
logic program. Since the result of our translation is an extended logic
program, we can make use of existing implementations, such as dlv and smodels.
To this end, we have developed a compiler, available on the web, as a front-end
for these programming systems
Strange Quark Contribution to the Nucleon Spin from Electroweak Elastic Scattering Data
The total contribution of strange quarks to the intrinsic spin of the nucleon
can be determined from a measurement of the strange-quark contribution to the
nucleon's elastic axial form factor. We have studied the strangeness
contribution to the elastic vector and axial form factors of the nucleon, using
elastic electroweak scattering data. Specifically, we combine elastic
and scattering cross section data from the Brookhaven E734
experiment with elastic and quasi-elastic and -He scattering
parity-violating asymmetry data from the SAMPLE, HAPPEx, G0 and PVA4
experiments. We have not only determined these form factors at individual
values of momentum-transfer (), but also have fit the -dependence of
these form factors using simple functional forms. We present the results of
these fits, along with some expectations of how our knowledge of these form
factors can be improved with data from Fermilab experiments.Comment: 3 pages, 1 figure, CIPANP 201
Auswirkungen der Schweizer Drogenpolitik aus Sicht der Suchtforschung
Die bewährte Viersäulenpolitik ist seit 2011 zusammen mit der heroingestützten Behandlung im Betäubungsmittelgesetz verankert und die Arbeitsteilung zwischen Bund und Kantonen darin geregelt. Die Cannabispolitik hingegen ist gescheitert. Probleme bestehen in der ungleichen Versorgung mit wissenschaftlich nachweislich wirksamen Behandlungsoptionen und niederschwelligen Angeboten auf kantonaler und regionaler Ebene. Ob den im Gesetz verankerten Verbesserungen des Jugendschutzes und dem Ordnungsbussenmodell für Cannabis eine Senkung des Drogenkonsums bei Jugendlichen folgt, muss evaluiert werden
Surface structure of i-Al(68)Pd(23)Mn(9): An analysis based on the T*(2F) tiling decorated by Bergman polytopes
A Fibonacci-like terrace structure along a 5fold axis of i-Al(68)Pd(23)Mn(9)
monograins has been observed by T.M. Schaub et al. with scanning tunnelling
microscopy (STM). In the planes of the terraces they see patterns of dark
pentagonal holes. These holes are well oriented both within and among terraces.
In one of 11 planes Schaub et al. obtain the autocorrelation function of the
hole pattern. We interpret these experimental findings in terms of the
Katz-Gratias-de Boisseu-Elser model. Following the suggestion of Elser that the
Bergman clusters are the dominant motive of this model, we decorate the tiling
T*(2F) by the Bergman polytopes only. The tiling T*(2F) allows us to use the
powerful tools of the projection techniques. The Bergman polytopes can be
easily replaced by the Mackay polytopes as the decoration objects. We derive a
picture of ``geared'' layers of Bergman polytopes from the projection
techniques as well as from a huge patch. Under the assumption that no surface
reconstruction takes place, this picture explains the Fibonacci-sequence of the
step heights as well as the related structure in the terraces qualitatively and
to certain extent even quantitatively. Furthermore, this layer-picture requires
that the polytopes are cut in order to allow for the observed step heights. We
conclude that Bergman or Mackay clusters have to be considered as geometric
building blocks of the i-AlPdMn structure rather than as energetically stable
entities
The Tilting Space of Boundary Conformal Field Theories
In boundary conformal field theories, global symmetries can be broken by
boundary conditions, generating a homogeneous conformal manifold. We
investigate these geometries, showing they have a coset structure, and give
fully worked out examples in the case of free fields of spin zero and one-half.
These results give a simple illustration of the salient features of conformal
manifolds while generalising to interacting and more intricate setups. Our work
was inspired by [2203.17157]Comment: 5 page
Taking an ethics of care perspective on two university teacher training programmes
This paper shows the usefulness and interest of taking an ethics of care perspective to evaluate university teacher training programmes. More precisely, in this case study we use the five elements of care identified by Tronto – attentiveness, responsibility, competence, responsiveness and trust – to assess two multiple-day training programmes offered at the University of Geneva. We show how small changes in our practice such as giving some choice to the participants over the topics addressed, adapting the schedule to meet the participants’ constraints or dedicating time slots specifically for the questions and concerns raised by the participants can have a big impact on the level of care provided. We moreover argue that this framework brings interesting and novel elements that appropriately “counterbalances” traditional evaluations that are usually implicitly based on notions such as performance, efficiency and measurability. Finally, we briefly explain how the ethics of care could be used a basis to not only evaluate but to rethink and elaborate training programmes
Non-isotropic Persistent Homology: Leveraging the Metric Dependency of PH
Persistent Homology is a widely used topological data analysis tool that
creates a concise description of the topological properties of a point cloud
based on a specified filtration. Most filtrations used for persistent homology
depend (implicitly) on a chosen metric, which is typically agnostically chosen
as the standard Euclidean metric on . Recent work has tried to
uncover the 'true' metric on the point cloud using distance-to-measure
functions, in order to obtain more meaningful persistent homology results. Here
we propose an alternative look at this problem: we posit that information on
the point cloud is lost when restricting persistent homology to a single
(correct) distance function. Instead, we show how by varying the distance
function on the underlying space and analysing the corresponding shifts in the
persistence diagrams, we can extract additional topological and geometrical
information. Finally, we numerically show that non-isotropic persistent
homology can extract information on orientation, orientational variance, and
scaling of randomly generated point clouds with good accuracy and conduct some
experiments on real-world data.Comment: 30 pages, 17 figures, comments welcome
Topological Point Cloud Clustering
We present Topological Point Cloud Clustering (TPCC), a new method to cluster
points in an arbitrary point cloud based on their contribution to global
topological features. TPCC synthesizes desirable features from spectral
clustering and topological data analysis and is based on considering the
spectral properties of a simplicial complex associated to the considered point
cloud. As it is based on considering sparse eigenvector computations, TPCC is
similarly easy to interpret and implement as spectral clustering. However, by
focusing not just on a single matrix associated to a graph created from the
point cloud data, but on a whole set of Hodge-Laplacians associated to an
appropriately constructed simplicial complex, we can leverage a far richer set
of topological features to characterize the data points within the point cloud
and benefit from the relative robustness of topological techniques against
noise. We test the performance of TPCC on both synthetic and real-world data
and compare it with classical spectral clustering
- …