Data Handover: Reconciling Message Passing and Shared Memory

Data Handover (DHO) is a programming paradigm and interface that aims to handle data between parallel or distributed processes that mixes aspects of message passing and shared memory. It is designed to overcome the potential problems in terms of efficiency of both: (1) memory blowup and forced copies for message passing and (2) data consistency and latency problems for shared memory. Our approach attempts to be simple and easy to understand. It contents itself with just a handful of functions to cover the main aspects of coarse grained inter-operation upon data

Reflexions on Urban Gardening in Germany

This article reflects on traditional and contemporary gardening movements in Germany. The focus is on forms of gardening, that take place in spaces subject to land lease agreements and similar forms of tenancy or of illegal land take or squatting. The author examines various definitions taking into account the variety of practices, the development of urban gardening over time, and the respective backgrounds or values that users relate to such gardening activities. The examination of definitions led to the drawing up of a timeline of traditional and contemporary gardening movements in Germany and to the tentative approaching of this issue from a semantic perspective. The latter is due to the usage of many different terms mostly as yet undefined in a legal sense. Translation into English or, most likely, to any other language, further blurs the common understanding of the terms used. The author concludes with some considerations on these gardening movements in relation to urban sustainable developments. A presentation at the 5th Rencontres Internationals de Reims on Sustainability Studies, dedicated to Urban Agriculture – Fostering the Urban-Rural Continuum, which took place in October 2015 in Reims/France was the starting point of this article. The basis of this article is a literature review, nourished to a certain extent by observations randomly made over many years and complemented through talks with competent young colleagues. Special thanks go to Martin Sondermann, Leibniz University Hannover, who shared his research experience in various discussions with the author, as well as to Friederike Stelter, internship student at the author’s place of work, who gave highly appreciated support to the preparation of the presentation

Reflexions on Urban Gardening in Germany

This article reflects on traditional and contemporary gardening movements in Germany. The focus is on forms of gardening, that take place in spaces subject to land lease agreements and similar forms of tenancy or of illegal land take or squatting. The author examines various definitions taking into account the variety of practices, the development of urban gardening over time, and the respective backgrounds or values that users relate to such gardening activities. The examination of definitions led to the drawing up of a timeline of traditional and contemporary gardening movements in Germany and to the tentative approaching of this issue from a semantic perspective. The latter is due to the usage of many different terms mostly as yet undefined in a legal sense. Translation into English or, most likely, to any other language, further blurs the common understanding of the terms used. The author concludes with some considerations on these gardening movements in relation to urban sustainable developments. A presentation at the 5th Rencontres Internationals de Reims on Sustainability Studies, dedicated to Urban Agriculture - Fostering the Urban-Rural Continuum, which took place in October 2015 in Reims/France was the starting point of this article. The basis of this article is a literature review, nourished to a certain extent by observations randomly made over many years and complemented through talks with competent young colleagues. Special thanks go to Martin Sondermann, Leibniz University Hannover, who shared his research experience in various discussions with the author, as well as to Friederike Stelter, internship student at the author’s place of work, who gave highly appreciated support to the preparation of the presentation

Efficient union-find for planar graphs and other sparse graph classes

AbstractWe solve the Union-Find Problem (UF) efficiently for the case the input is restricted to several graph classes, namely partial k-trees for any fixed k, d-dimensional grids for any fixed dimension d and for planar graphs. The result on grids allows us to perform region growing techniques that are used for image segmentation in linear time. For planar graphs we develop a technique of decomposing such a graph into small subgraphs, patching, that might be useful for other algorithmic problems on planar graphs, too.By efficiency we do not only mean linear time in a theoretical setting but also a practical reorganization of memory such that a dynamic data structures for UF is allocated consecutively

Emerging legal theories of educational malpractice and judicial rejection

This is a study of the current legal theories, elements, and courts’ stances affecting educational malpractice litigation. General and legal issues were researched as a basis to identify court attitudes and general public pressures. The study also took a look at the question of possible avenues for dealing with problems of educational malpractice. Should the courts decide why Johnny can’t read and award monetary damages? Should the legislature deal with the problem of faulty education, or should a totally different agency become involved in such an undertaking? Related fields, such as medical malpractice, torts, contract theory, and responsiblities and obligations of students in the educational system, were examined as well. Will suites of educational malpractice succeed? Should they succeed? The question of the likelihood of educational malpractice suits to succeed is also dealt with, based on the decided cases of Hoffman v. Board of Education, Donohue v. Copiague Union Free School District, Peter W. v. San Francisco Unified School District, Pauley v. Kelley, and related holdings. Suggestions for alternative approaches to educational malpractice are proposed

An experimental validation of the PRO model for parallel and distributed computation

National audienceThe Parallel Resource-Optimal (PRO) computation model was introduced by Gebremedhin et al. [2002] as a framework for the design and analysis of efficient parallel algorithms. The key features of the PRO model that distinguish it from previous parallel computation models are the full integration of resource-optimality into the design process and the use of a {granularity function as a parameter for measuring quality. In this paper we present experimental results on parallel algorithms, designed using the PRO model, for two representative problems: list ranking and sorting. The algorithms are implemented using SSCRAP, our environment for developing coarse-grained algorithms. The experimental performance results observed agree well with analytical predictions using the PRO model. Moreover, by using different platforms to run our experiments, we have been able to provide an integrated view of the modeling of an underlying architecture and the design and implementation of scalable parallel algorithms

Institutional differences in Germany and France: between spatial reform and persistence

Germany and France offer two different models of political and administrative organisation: a federal state on one side of the Rhine and a unitary state on the other, albeit one that has become more decentralised over the last 40 years. Thus, the French régions have reduced capacities for action compared to the Länder. At the local level, the administrative structure was strengthened in Germany by merging municipalities, whereas France chose to use intermunicipal structures. In contrast to the political and administrative stability in Germany, local and regional organisation in France is constantly evolving, faced with a succession of laws, the pace of which has accelerated over time. The same applies to spatial planning, which has been framed from the outset by the German Grundgesetz (GG - Basic Law), but which has undergone much more evolution on the French side, even if the loi d'orientation foncière (LOF - Basic Land Act) of 1967 and the loi solidarité et renouvellement urbain (SRU - Law on Urban Solidarity and Renewal) (2000) represent two fundamental stages. In both countries, the strategic dimension of planning has been strengthened, and each side has developed its own tools for the management of urban projects

Resource Centered Computing delivering high parallel performance

International audienceModern parallel programming requires a combination of differentparadigms, expertise and tuning, that correspond to the differentlevels in today's hierarchical architectures. To cope with theinherent difficulty, ORWL (ordered read-write locks) presents a newparadigm and toolbox centered around local or remote resources, suchas data, processors or accelerators. ORWL programmers describe theircomputation in terms of access to these resources during criticalsections. Exclusive or shared access to the resources is grantedthrough FIFOs and with read-write semantic. ORWL partially replaces aclassical runtime and offers a new API for resource centric parallelprogramming. We successfully ran an ORWL benchmark application ondifferent parallel architectures (a multicore CPU cluster, a NUMAmachine, a CPU+GPU cluster). When processing large data we achievedscalability and performance similar to a reference code built on topof MPI+OpenMP+CUDA. The integration of optimized kernels of scientificcomputing libraries (ATLAS and cuBLAS) has been almost effortless, andwe were able to increase performance using both CPU and GPU cores onour hybrid hierarchical cluster simultaneously. We aim to make ORWL anew easy-to-use and efficient programming model and toolbox forparallel developers

Grid classes and partial well order

We prove necessary and sufficient conditions on a family of (generalised) gridding matrices to determine when the corresponding permutation classes are partially well-ordered. One direction requires an application of Higman's Theorem and relies on there being only finitely many simple permutations in the only non-monotone cell of each component of the matrix. The other direction is proved by a more general result that allows the construction of infinite antichains in any grid class of a matrix whose graph has a component containing two or more non-monotone-griddable cells. The construction uses a generalisation of pin sequences to grid classes, together with a number of symmetry operations on the rows and columns of a gridding.Comment: 22 pages, 7 figures. To appear in J. Comb. Theory Series