376,491 research outputs found
Theory of Coster-Kronig preceded Auger processes in solids
We propose the foundations of an extended Auger line-shape analysis of solids aiming to include three-hole features such as the ones due to core-valence-valence Auger decays following Coster-Kronig transitions. In transition metals, such features show up as intense high binding energy satellites of the diagrammatic core-valence-valence lines. Our theory is grounded on the full one-step approach, but to keep the complications to a minimum, in the present exploratory paper, the valence band is assumed fully below the Fermi level. In this way, explicit model calculations can be confidently based on a three-step approach. The line-shape analysis then amounts to compute a three-body Green's function, which, however, is much less known than one- and two-body ones. Our treatment covers the whole range between weak and strong correlations. Furthermore, we show that the relevant physics can be captured by a transparent, computationally simple closed formula. We find that, in general, the satellites cover separated spectral regions with three-hole multiplets, shifted and broadened two-hole features, and distorted bandlike continua
Prediction of Search Targets From Fixations in Open-World Settings
Previous work on predicting the target of visual search from human fixations
only considered closed-world settings in which training labels are available
and predictions are performed for a known set of potential targets. In this
work we go beyond the state of the art by studying search target prediction in
an open-world setting in which we no longer assume that we have fixation data
to train for the search targets. We present a dataset containing fixation data
of 18 users searching for natural images from three image categories within
synthesised image collages of about 80 images. In a closed-world baseline
experiment we show that we can predict the correct target image out of a
candidate set of five images. We then present a new problem formulation for
search target prediction in the open-world setting that is based on learning
compatibilities between fixations and potential targets
Wild ramification kinks
Given a branched cover between smooth projective curves over a
non-archimedian mixed-characteristic local field and an open rigid disk
, we study the question under which conditions the inverse image
is again an open disk. More generally, if the cover varies in
an analytic family, is this true at least for some member of the family? Our
main result gives a criterion for this to happen.Comment: Final version, to appear in Research in the Mathematical Sciences. 29
page
Redundancy, Deduction Schemes, and Minimum-Size Bases for Association Rules
Association rules are among the most widely employed data analysis methods in
the field of Data Mining. An association rule is a form of partial implication
between two sets of binary variables. In the most common approach, association
rules are parameterized by a lower bound on their confidence, which is the
empirical conditional probability of their consequent given the antecedent,
and/or by some other parameter bounds such as "support" or deviation from
independence. We study here notions of redundancy among association rules from
a fundamental perspective. We see each transaction in a dataset as an
interpretation (or model) in the propositional logic sense, and consider
existing notions of redundancy, that is, of logical entailment, among
association rules, of the form "any dataset in which this first rule holds must
obey also that second rule, therefore the second is redundant". We discuss
several existing alternative definitions of redundancy between association
rules and provide new characterizations and relationships among them. We show
that the main alternatives we discuss correspond actually to just two variants,
which differ in the treatment of full-confidence implications. For each of
these two notions of redundancy, we provide a sound and complete deduction
calculus, and we show how to construct complete bases (that is,
axiomatizations) of absolutely minimum size in terms of the number of rules. We
explore finally an approach to redundancy with respect to several association
rules, and fully characterize its simplest case of two partial premises.Comment: LMCS accepted pape
Counting matroids in minor-closed classes
A flat cover is a collection of flats identifying the non-bases of a matroid.
We introduce the notion of cover complexity, the minimal size of such a flat
cover, as a measure for the complexity of a matroid, and present bounds on the
number of matroids on elements whose cover complexity is bounded. We apply
cover complexity to show that the class of matroids without an -minor is
asymptotically small in case is one of the sparse paving matroids
, , , , or , thus confirming a few special
cases of a conjecture due to Mayhew, Newman, Welsh, and Whittle. On the other
hand, we show a lower bound on the number of matroids without -minor
which asymptoticaly matches the best known lower bound on the number of all
matroids, due to Knuth.Comment: 13 pages, 3 figure
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