33,218 research outputs found
Definability Equals Recognizability for -Outerplanar Graphs
One of the most famous algorithmic meta-theorems states that every graph
property that can be defined by a sentence in counting monadic second order
logic (CMSOL) can be checked in linear time for graphs of bounded treewidth,
which is known as Courcelle's Theorem. These algorithms are constructed as
finite state tree automata, and hence every CMSOL-definable graph property is
recognizable. Courcelle also conjectured that the converse holds, i.e. every
recognizable graph property is definable in CMSOL for graphs of bounded
treewidth. We prove this conjecture for -outerplanar graphs, which are known
to have treewidth at most .Comment: 40 pages, 8 figure
Stratified fibre bundles
A stratified bundle is a fibered space in which strata are classical bundles
and in which attachment of strata is controlled by a structure category of
fibers. Well known results on fibre bundles are shown to be true for stratified
bundles; namely the pull back theorem, the bundle theorem and the principal
bundle theorem.Comment: LaTeX file. Revised version. Accepted for publication on "Forum
Mathematicum
The Pioneer Anomaly and a Rotating G\"odel Universe
Based upon a simple cosmological model with no expansion, we find that the
rotational terms appearing in the G/"odel universe are too small to explain the
Pioneer anomaly. Although it contributes, universal rotation is not the cause
of the Pioneer effect.Comment: 13 pages, 2 figure
K-theory of stratified vector bundles
We show that the Atiyah-Hirzebruch K-theory of spaces admits a canonical
generalization for stratified spaces. For this we study algebraic constructions
on stratified vector bundles. In particular the tangent bundle of a stratified
manifold is such a stratified vector bundle.Comment: LaTeX file, 22 page
Macroservers: An Execution Model for DRAM Processor-In-Memory Arrays
The emergence of semiconductor fabrication technology allowing a tight coupling between high-density DRAM and CMOS logic on the same chip has led to the important new class of Processor-In-Memory (PIM) architectures. Newer developments provide powerful parallel processing capabilities on the chip, exploiting the facility to load wide words in single memory accesses and supporting complex address manipulations in the memory. Furthermore, large arrays of PIMs can be arranged into a massively parallel architecture. In this report, we describe an object-based programming model based on the notion of a macroserver. Macroservers encapsulate a set of variables and methods; threads, spawned by the activation of methods, operate asynchronously on the variables' state space. Data distributions provide a mechanism for mapping large data structures across the memory region of a macroserver, while work distributions allow explicit control of bindings between threads and data. Both data and work distributuions are first-class objects of the model, supporting the dynamic management of data and threads in memory. This offers the flexibility required for fully exploiting the processing power and memory bandwidth of a PIM array, in particular for irregular and adaptive applications. Thread synchronization is based on atomic methods, condition variables, and futures. A special type of lightweight macroserver allows the formulation of flexible scheduling strategies for the access to resources, using a monitor-like mechanism
Grundmannite, CuBiSe2, the Se-analogue of emplectite, a new mineral from the El Dragón mine, Potosí, Bolivia
© 2016 E. Schweizerbart'sche Verlagsbuchhandlung Science Publishers. Also published by
Deutsche Mineralogische Gesellschaft, Sociedad Española de Mineralogía, Società Italiana di Mineralogia e Petrologia, Société Française de Minéralogie et de Cristallographie under the auspices of the European Mineralogical Union. This document attached is the author's submitted version of the journal article. You are advised to consult the publisher's version if you wish to cite from it
Wage-Price Dynamics and Deflation in Hong Kong
This paper provides empirical evidence on the dynamics of prices and wages in Hong Kong. The results imply that the deflation in Hong Kong since 1997 can be understood using a conventional macroeconomic framework wherein foreign influences constitute the basic underlying shocks, and adjustment processes in domestic wages and prices determine the details of the transmission mechanism. Our results indicate that the decline in local nominal prices owes much to declining prices of imported intermediate goods. The negative output gap and the increase in unemployment experienced during the deflation period also have their origin in foreign shocks, but the domestic wage adjustment process constitutes an important contributing factor.Deflation, wage-price dynamics, Hong Kong data.
Speeding-up Dynamic Programming with Representative Sets - An Experimental Evaluation of Algorithms for Steiner Tree on Tree Decompositions
Dynamic programming on tree decompositions is a frequently used approach to
solve otherwise intractable problems on instances of small treewidth. In recent
work by Bodlaender et al., it was shown that for many connectivity problems,
there exist algorithms that use time, linear in the number of vertices, and
single exponential in the width of the tree decomposition that is used. The
central idea is that it suffices to compute representative sets, and these can
be computed efficiently with help of Gaussian elimination.
In this paper, we give an experimental evaluation of this technique for the
Steiner Tree problem. A comparison of the classic dynamic programming algorithm
and the improved dynamic programming algorithm that employs the table reduction
shows that the new approach gives significant improvements on the running time
of the algorithm and the size of the tables computed by the dynamic programming
algorithm, and thus that the rank based approach from Bodlaender et al. does
not only give significant theoretical improvements but also is a viable
approach in a practical setting, and showcases the potential of exploiting the
idea of representative sets for speeding up dynamic programming algorithms
- …