1,720,977 research outputs found
Minimum Mean Cycle Instances
No full textThis data set contains some large real-world instances of the minimum mean cycle problem.
They are reported as the bonn01 to bonn09 instances in the paper:
Georgiadis, L., Goldberg, A. V., Tarjan, R. E., & Werneck, R. F.
"An experimental study of minimum mean cycle algorithms",
in 2009 Proceedings of the Eleventh Workshop on Algorithm Engineering and Experiments (ALENEX), pp. 1–13,
SIAM.
The instances arise in clock skew scheduling in chip design, e.g. see
Held, S., Korte, B., Rautenbach, D. and Vygen, J.
"Combinatorial optimization in VLSI design. Combinatorial Optimization",
in Combinatorial Optimization, NATO Science for Peace and Security Series - D: Information and Communication Security, pp. 33–96, 2011.
The clock skew scheduling problem in chip design is, given a directed graph G with edge delays d:E(G)-> R,
find a minimum cycle time T and arrival times (a schedule) a: V(G) -> R such that
a(v) + d(v,w) <= a(w) + T for all (v,w) in E(G).
G is called a latch graph. The nodes represent latches and registers, and the edges represent the longest signal paths between registers.
The problem of minimizing T is equivalent to maximizing the worst slack min{s(v,w) := a(w) + T - a(v) - d(v,w) | (v,w) in E(G)} for a fixed cycle time T.
The instances provided in the tar file below consist of directed graphs with edge costs c(v,w) = T - d(v,w),
i.e. edge slacks w.r.t. a zero-skew schedule where a = 0.
The maximum achievable worst slack by varying the schedule 'a' equals the value of a minimum mean cycle in (G,c).
Instance sizes range from 70346 nodes and 898220 edges to 1065274 nodes and 104340248 edges.
Other instances are very dense, e.g. 5361 nodes and 4169878 edges.
Note that the instances may not be strongly connected or even connected.
Format: Ignore empty lines and lines starting with '#', then:
1st line: number_of_nodes number_of_edges
next lines: from_node to_node edge_cost (i.e., zero skew slack
Large Benchmarks for the Minimum-Cost Flow Problem
No full textMinimum cost flow instance generated at the Research Institute for
Discrete Mathematics, University of Bonn.
Contact: Stephan Held ([email protected])
These instances arise in VLSI placement legalization (LEGALIZATION
subdir) or as linear relaxation of the discrete time-cost tradeoff
problem used for voltage threshold assignment (TCT subdir).
The LEGALIZATION instances are significantly harder to solve than the
TCT instances.
All instances are provided in the DIMACS networks format that is specified here:
http://archive.dimacs.rutgers.edu/Challenges/
http://archive.dimacs.rutgers.edu/pub/netflow/general-info/specs.te
Chromatic Numbers from Exact Decision Diagrams in Exact Arithmetic
No full textThis dataset contains source code and consoles for computing chromatic numbers
with exact decision diagrams, solving integer programs with exact arithmetic.
The chromatic number of the DIMACS instance r1000.1c could be determined
for the first time.
There are 3 files:
- ddruns_main.zip contains scripts to reproduce the results
- ddruns.tar contains the consoles and SCIP-exact certificates from our exeriments
- ddcolors_flow_extraction.zip contains the C++ source code to compute exact decision diagrams for graph coloring
BonnTour: benchmarks & solutions for vehicle routing with time-dependent travel times
No full textThis repository contains the new vehicle routing benchmark instances that we created as part of our work on vehicle routing with time-dependent travel times.
To create this benchmark set, we used map data copyrighted by OpenStreetMap contributors and available from https://www.openstreetmap.org under the Open Database License (ODbL) v1.0, and speed data retrieved from Uber Movement, (c) 2022 Uber Technologies, Inc., https://movement.uber.com, under a Creative Commons Attribution Non-Commercial license.
The solutions reported in the related publication
Jannis Blauth, Stephan Held, Dirk Müller, Niklas Schlomberg, Vera Traub, Thorben Tröbst, Jens Vygen:
Vehicle routing with time-dependent travel times: Theory, practice, and benchmarks.
Discrete Optimization, Volume 53, 2024, 100848.
are also contained.
This repository is a snapshot of https://gitlab.com/muelleratorunibonnde/vrptdt-benchmark (git revision: 1306f4b22a5ecf3307ed), i.e. the version that was used in the above publication
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
- …
