224 research outputs found
On the cost-complexity of multi-context systems
Multi-context systems provide a powerful framework for modelling
information-aggregation systems featuring heterogeneous reasoning components.
Their execution can, however, incur non-negligible cost. Here, we focus on
cost-complexity of such systems. To that end, we introduce cost-aware
multi-context systems, an extension of non-monotonic multi-context systems
framework taking into account costs incurred by execution of semantic operators
of the individual contexts. We formulate the notion of cost-complexity for
consistency and reasoning problems in MCSs. Subsequently, we provide a series
of results related to gradually more and more constrained classes of MCSs and
finally introduce an incremental cost-reducing algorithm solving the reasoning
problem for definite MCSs
Magnetic circular dichroism in EELS: Towards 10 nm resolution
We describe a new experimental setup for the detection of magnetic circular
dichroism with fast electrons (EMCD). As compared to earlier findings the
signal is an order of magnitude higher, while the probed area could be
significantly reduced, allowing a spatial resolution of the order of 30 nm. A
simplified analysis of the experimental results is based on the decomposition
of the Mixed Dynamic Form Factor S(q,q',E) into a real part related to the
scalar product and an imaginary part related to the vector product of the
scattering vectors q and q'. Following the recent detection of chiral
electronic transitions in the electron microscope the present experiment is a
crucial demonstration of the potential of EMCD for nanoscale investigations.Comment: 12 pages, 6 figures, submitted to Ultramicroscop
Spatiotemporal databases: Models for attracting students to research
In higher education professors often make much effort to introduce their students to research. Unfortunately, the present standard database systems curriculum is composed of well-settled subjects that do not lead to research. The challenge is to bring the research frontier closer to students at beginner level. In this paper we describe how it can be done in the area of spatiotemporal databases. We propose a new database systems curriculum and illustrate its benefits by mentioning several highly succsesful student projects in some recent experimental introductory database systems courses that followed the new curriculum
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