2,884 research outputs found
Universal Loop-Free Super-Stabilization
We propose an univesal scheme to design loop-free and super-stabilizing
protocols for constructing spanning trees optimizing any tree metrics (not only
those that are isomorphic to a shortest path tree). Our scheme combines a novel
super-stabilizing loop-free BFS with an existing self-stabilizing spanning tree
that optimizes a given metric. The composition result preserves the best
properties of both worlds: super-stabilization, loop-freedom, and optimization
of the original metric without any stabilization time penalty. As case study we
apply our composition mechanism to two well known metric-dependent spanning
trees: the maximum-flow tree and the minimum degree spanning tree
Disconnected components detection and rooted shortest-path tree maintenance in networks
International audienceMany articles deal with the problem of maintaining a rooted shortest-path tree. However, after some edge deletions, some nodes can be disconnected from the connected component of some distinguished node . In this case, an additional objective is to ensure the detection of the disconnection by the nodes that no longer belong to . We present a detailed analysis of a silent self-stabilizing algorithm. We prove that it solves this more demanding task in anonymous weighted networks with the following additional strong properties: it runs without any knowledge on the network and under the \emph{unfair} daemon, that is without any assumption on the asynchronous model. Moreover, it terminates in less than rounds for a network of nodes and hop-diameter
Sandpile models
This survey is an extended version of lectures given at the Cornell
Probability Summer School 2013. The fundamental facts about the Abelian
sandpile model on a finite graph and its connections to related models are
presented. We discuss exactly computable results via Majumdar and Dhar's
method. The main ideas of Priezzhev's computation of the height probabilities
in 2D are also presented, including explicit error estimates involved in
passing to the limit of the infinite lattice. We also discuss various questions
arising on infinite graphs, such as convergence to a sandpile measure, and
stabilizability of infinite configurations.Comment: 72 pages - v3 incorporates referee's comments. References closely
related to the lectures were added/update
Primer for the algebraic geometry of sandpiles
The Abelian Sandpile Model (ASM) is a game played on a graph realizing the
dynamics implicit in the discrete Laplacian matrix of the graph. The purpose of
this primer is to apply the theory of lattice ideals from algebraic geometry to
the Laplacian matrix, drawing out connections with the ASM. An extended summary
of the ASM and of the required algebraic geometry is provided. New results
include a characterization of graphs whose Laplacian lattice ideals are
complete intersection ideals; a new construction of arithmetically Gorenstein
ideals; a generalization to directed multigraphs of a duality theorem between
elements of the sandpile group of a graph and the graph's superstable
configurations (parking functions); and a characterization of the top Betti
number of the minimal free resolution of the Laplacian lattice ideal as the
number of elements of the sandpile group of least degree. A characterization of
all the Betti numbers is conjectured.Comment: 45 pages, 14 figures. v2: corrected typo
Dynamical Fractional Chaotic Inflation -- Dynamical Generation of a Fractional Power-Law Potential for Chaotic Inflation
Chaotic inflation based on a simple monomial scalar potential, V(phi) ~
phi^p, is an attractive large-field model of inflation capable of generating a
sizable tensor-to-scalar ratio r. Therefore, assuming that future CMB
observations will confirm the large r value reported by BICEP2, it is important
to determine what kind of dynamical mechanism could possibly endow the inflaton
field with such a simple effective potential. In this paper, we answer this
question in the context of field theory, i.e. in the framework of dynamical
chaotic inflation (DCI), where strongly interacting supersymmetric gauge
dynamics around the scale of grand unification dynamically generate a
fractional power-law potential via the quantum effect of dimensional
transmutation. In constructing explicit models, we significantly extend our
previous work, as we now consider a large variety of possible underlying gauge
dynamics and relax our conditions on the field content of the model. This
allows us to realize almost arbitrary rational values for the power p in the
inflaton potential. The present paper may hence be regarded as a first step
towards a more complete theory of dynamical chaotic inflation.Comment: 68 pages, 7 figures, 2 tables, 2 appendice
Polynomial Silent Self-Stabilizing p-Star Decomposition
We present a silent self-stabilizing distributed algorithm computing a maximal p-star decomposition of the underlying communication network. Under the unfair distributed scheduler, the most general scheduler model, the algorithm converges in at most 12∆m + O(m + n) moves, where m is the number of edges, n is the number of nodes, and ∆ is the maximum node degree. Regarding the move complexity, our algorithm outperforms the previously known best algorithm by a factor of ∆. While the round complexity for the previous algorithm was unknown, we show a 5 [n/(p+1)] + 5 bound for our algorithm
Pati-Salam Axion
I discuss the implementation of the Peccei-Quinn mechanism in a minimal
realization of the Pati-Salam partial unification scheme. The axion mass is
shown to be related to the Pati-Salam breaking scale and it is predicted via a
two-loop renormalization group analysis to be in the window eV, as a function of a sliding Left-Right symmetry
breaking scale. This parameter space will be fully covered by the late phases
of the axion Dark Matter experiments ABRACADABRA and CASPEr-Electric. A
Left-Right symmetry breaking scenario as low as 20 TeV is obtained for a
Pati-Salam breaking of the order of the reduced Planck mass.Comment: 33 pages, 3 figures. Minor corrections. Matches version to appear in
JHE
Chip-Firing and Rotor-Routing on Directed Graphs
We give a rigorous and self-contained survey of the abelian sandpile model
and rotor-router model on finite directed graphs, highlighting the connections
between them. We present several intriguing open problems.Comment: 34 pages, 11 figures. v2 has additional references, v3 corrects
figure 9, v4 corrects several typo
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