16,092 research outputs found
Parameterized Complexity of Equitable Coloring
A graph on vertices is equitably -colorable if it is -colorable and
every color is used either or times.
Such a problem appears to be considerably harder than vertex coloring, being
even for cographs and interval graphs.
In this work, we prove that it is for block
graphs and for disjoint union of split graphs when parameterized by the number
of colors; and for -free interval graphs
when parameterized by treewidth, number of colors and maximum degree,
generalizing a result by Fellows et al. (2014) through a much simpler
reduction.
Using a previous result due to Dominique de Werra (1985), we establish a
dichotomy for the complexity of equitable coloring of chordal graphs based on
the size of the largest induced star.
Finally, we show that \textsc{equitable coloring} is when
parameterized by the treewidth of the complement graph
Plastic Deformation of 2D Crumpled Wires
When a single long piece of elastic wire is injected trough channels into a
confining two-dimensional cavity, a complex structure of hierarchical loops is
formed. In the limit of maximum packing density, these structures are described
by several scaling laws. In this paper it is investigated this packing process
but using plastic wires which give origin to completely irreversible structures
of different morphology. In particular, it is studied experimentally the
plastic deformation from circular to oblate configurations of crumpled wires,
obtained by the application of an axial strain. Among other things, it is shown
that in spite of plasticity, irreversibility, and very large deformations,
scaling is still observed.Comment: 5 pages, 6 figure
Polynomial Realization of and Fusion Rules at Exceptional Values of
Representations of the algebra are constructed in the space of
polynomials of real (complex) variable for . The spin addition rule
based on eigenvalues of Casimir operator is illustrated on few simplest cases
and conjecture for general case is formulated
The 1/N Expansion in Noncommutative Quantum Mechanics
We study the 1/N expansion in noncommutative quantum mechanics for the
anharmonic and Coulombian potentials. The expansion for the anharmonic
oscillator presented good convergence properties, but for the Coulombian
potential, we found a divergent large N expansion when using the usual
noncommutative generalization of the potential. We proposed a modified version
of the noncommutative Coulombian potential which provides a well-behaved 1/N
expansion.Comment: v2: resided version, to appear in PRD, 18 pages, 4 figure
Método de obtenção qualificada de fenótipos visando à avaliação de genótipos bovinos resistentes ao carrapato Rhipicephalus (Boophilus) microplus.
Formação de grupos de manejo; Determinação correta do momento da mensuração da carga parasitária; Controle parasitário durante o período de avaliação; Padronização da técnica de contagem de carrapatos; Registro de dados; Análise dos dados.bitstream/item/31735/1/CO-75-online.pd
Effective models of quantum gravity induced by Planck scale modifications in the covariant quantum algebra
In this paper we introduce a modified covariant quantum algebra based in the
so-called Quesne-Tkachuk algebra. By means of a deformation procedure we arrive
at a class of higher derivative models of gravity. The study of the particle
spectra of these models reveals an equivalence with the physical content of the
well-known renormalizable and super-renormalizable higher derivative gravities.
The particle spectrum exhibits the presence of spurious complex ghosts and, in
light of this problem, we suggest an interesting interpretation in the context
of minimal length theories. Also, a discussion regarding the non-relativistic
potential energy is proposed.Comment: Small corrections were made; improved figures; results unchanged;
published versio
Deciphering M-T diagram of shape memory Heusler alloys: reentrance, plateau and beyond
We present our recent results on temperature behaviour of magnetization
observed in Ni_47Mn_39In_14 Heusler alloys. Three regions can be distinguished
in the M-T diagram: (I) low temperature martensitic phase (with the Curie
temperature T_CM = 140 K), (II) intermediate mixed phase (with the critical
temperature T_MS = 230 K) exhibiting a reentrant like behavior (between T_CM
and T_MS) and (III) high temperature austenitic phase (with the Curie
temperature T_CA = 320 K) exhibiting a rather wide plateau region (between T_MS
and T_CA). By arguing that powerful structural transformations, causing drastic
modifications of the domain structure in alloys, would also trigger strong
fluctuations of the order parameters throughout the entire M-T diagram, we were
able to successfully fit all the data by incorporating Gaussian fluctuations
(both above and below the above three critical temperatures) into the
Ginzburg-Landau scenario
Radiative Corrections to the Aharonov-Bohm Scattering
We consider the scattering of relativistic electrons from a thin magnetic
flux tube and perturbatively calculate the order , radiative
correction, to the first order Born approximation. We show also that the second
order Born amplitude vanishes, and obtain a finite inclusive cross section for
the one-body scattering which incorporates soft photon bremsstrahlung effects.
Moreover, we determine the radiatively corrected Aharonov-Bohm potential and,
in particular, verify that an induced magnetic field is generated outside of
the flux tube.Comment: 14 pages, revtex, 3 figure
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