329,221 research outputs found
A T-partial order obtained from T-norms
summary:A partial order on a bounded lattice is called t-order if it is defined by means of the t-norm on . It is obtained that for a t-norm on a bounded lattice the relation iff for some is a partial order. The goal of the paper is to determine some conditions such that the new partial order induces a bounded lattice on the subset of all idempotent elements of and a complete lattice on the subset of all elements of which are the supremum of a subset of atoms
Reconstructing phase dynamics of oscillator networks
We generalize our recent approach to reconstruction of phase dynamics of
coupled oscillators from data [B. Kralemann et al., Phys. Rev. E, 77, 066205
(2008)] to cover the case of small networks of coupled periodic units. Starting
from the multivariate time series, we first reconstruct genuine phases and then
obtain the coupling functions in terms of these phases. The partial norms of
these coupling functions quantify directed coupling between oscillators. We
illustrate the method by different network motifs for three coupled oscillators
and for random networks of five and nine units. We also discuss nonlinear
effects in coupling.Comment: 6 pages, 5 figures, 27 reference
Beyond graph energy: norms of graphs and matrices
In 1978 Gutman introduced the energy of a graph as the sum of the absolute
values of graph eigenvalues, and ever since then graph energy has been
intensively studied.
Since graph energy is the trace norm of the adjacency matrix, matrix norms
provide a natural background for its study. Thus, this paper surveys research
on matrix norms that aims to expand and advance the study of graph energy.
The focus is exclusively on the Ky Fan and the Schatten norms, both
generalizing and enriching the trace norm. As it turns out, the study of
extremal properties of these norms leads to numerous analytic problems with
deep roots in combinatorics.
The survey brings to the fore the exceptional role of Hadamard matrices,
conference matrices, and conference graphs in matrix norms. In addition, a vast
new matrix class is studied, a relaxation of symmetric Hadamard matrices.
The survey presents solutions to just a fraction of a larger body of similar
problems bonding analysis to combinatorics. Thus, open problems and questions
are raised to outline topics for further investigation.Comment: 54 pages. V2 fixes many typos, and gives some new materia
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