31,213 research outputs found
On the structure of Ammann A2 tilings
We establish a structure theorem for the family of Ammann A2 tilings of the
plane. Using that theorem we show that every Ammann A2 tiling is self-similar
in the sense of [B. Solomyak, Nonperiodicity implies unique composition for
self-similar translationally finite tilings, Discrete and Computational
Geometry 20 (1998) 265-279]. By the same techniques we show that Ammann A2
tilings are not robust in the sense of [B. Durand, A. Romashchenko, A. Shen.
Fixed-point tile sets and their applications, Journal of Computer and System
Sciences, 78:3 (2012) 731--764]
A Discrete Choquet Integral for Ordered Systems
A model for a Choquet integral for arbitrary finite set systems is presented.
The model includes in particular the classical model on the system of all
subsets of a finite set. The general model associates canonical non-negative
and positively homogeneous superadditive functionals with generalized belief
functions relative to an ordered system, which are then extended to arbitrary
valuations on the set system. It is shown that the general Choquet integral can
be computed by a simple Monge-type algorithm for so-called intersection
systems, which include as a special case weakly union-closed families.
Generalizing Lov\'asz' classical characterization, we give a characterization
of the superadditivity of the Choquet integral relative to a capacity on a
union-closed system in terms of an appropriate model of supermodularity of such
capacities
A survey on algorithmic aspects of modular decomposition
The modular decomposition is a technique that applies but is not restricted
to graphs. The notion of module naturally appears in the proofs of many graph
theoretical theorems. Computing the modular decomposition tree is an important
preprocessing step to solve a large number of combinatorial optimization
problems. Since the first polynomial time algorithm in the early 70's, the
algorithmic of the modular decomposition has known an important development.
This paper survey the ideas and techniques that arose from this line of
research
Geodetic topological cycles in locally finite graphs
We prove that the topological cycle space C(G) of a locally finite graph G is
generated by its geodetic topological circles. We further show that, although
the finite cycles of G generate C(G), its finite geodetic cycles need not
generate C(G).Comment: 1
Approximation Error Bounds via Rademacher's Complexity
Approximation properties of some connectionistic models, commonly used to construct approximation schemes for optimization problems with multivariable functions as admissible solutions, are investigated. Such models are made up of linear combinations of computational units
with adjustable parameters. The relationship between model complexity (number of computational units) and approximation error is investigated using tools from Statistical Learning Theory, such as Talagrand's
inequality, fat-shattering dimension, and Rademacher's complexity. For some families of multivariable functions, estimates of the approximation accuracy of models with certain computational units are derived in dependence of the Rademacher's complexities of the families. The
estimates improve previously-available ones, which were expressed in terms of V C dimension and derived by exploiting union-bound techniques. The results are applied to approximation schemes with certain radial-basis-functions as computational units, for which it is shown that
the estimates do not exhibit the curse of dimensionality with respect to the number of variables
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