6,670 research outputs found
PACE Solver Description: Tree Depth with FlowCutter
Get PDFWe describe the FlowCutter submission to the PACE 2020 heuristic tree-depth challenge. The task of the challenge consists of computing an elimination tree of small height for a given graph. At its core our submission uses a nested dissection approach, with FlowCutter as graph bisection algorithm
Dynamic Time-Dependent Routing in Road Networks Through Sampling
Get PDFWe study the earliest arrival and profile problems in road networks with time-dependent functions as arc weights and dynamic updates. We present and experimentally evaluate simple, sampling-based, heuristic algorithms. Our evaluation is performed on large, current, production-grade road graph data with time-dependent arc weights. It clearly shows that the proposed algorithms are fast and compute paths with a sufficiently small error for most practical applications. We experimentally compare our algorithm against the current state-of-the-art. Our experiments reveal, that the memory consumption of existing algorithms is prohibitive on large instances. Our approach does not suffer from this limitation. Further, our algorithm is the only competitor able to answer profile queries on all test instances below 50ms. As our algorithm is simple to implement, we believe that it is a good fit for many realworld applications
A Fast and Tight Heuristic for A* in Road Networks
Get PDFWe study exact, efficient and practical algorithms for route planning in large road networks. Routing applications often require integrating the current traffic situation, planning ahead with traffic predictions for the future, respecting forbidden turns, and many other features depending on the exact application. While Dijkstra’s algorithm can be used to solve these problems, it is too slow for many applications. A* is a classical approach to accelerate Dijkstra’s algorithm. A* can support many extended scenarios without much additional implementation complexity. However, A*’s performance depends on the availability of a good heuristic that estimates distances. Computing tight distance estimates is a challenge on its own. On road networks, shortest paths can also be quickly computed using hierarchical speedup techniques. They achieve speed and exactness but sacrifice A*’s flexibility. Extending them to certain practical applications can be hard. In this paper, we present an algorithm to efficiently extract distance estimates for A* from Contraction Hierarchies (CH), a hierarchical technique. We call our heuristic CH-Potentials. Our approach allows decoupling the supported extensions from the hierarchical speed-up technique. Additionally, we describe A* optimizations to accelerate the processing of low degree nodes, which often occur in road networks
Space-Efficient, Fast and Exact Routing in Time-Dependent Road Networks
Get PDFWe study the problem of computing shortest paths in massive road networks with traffic predictions. Incorporating traffic predictions into routing allows, for example, to avoid commuter traffic congestions. Existing techniques follow a two-phase approach: In a preprocessing step, an index is built. The index depends on the road network and the traffic patterns but not on the path start and end. The latter are the input of the query phase, in which shortest paths are computed. All existing techniques have either large index size, slow query running times, or may compute suboptimal paths. In this work, we introduce CATCHUp (Customizable Approximated Time-dependent Contraction Hierarchies through Unpacking), the first algorithm that simultaneously achieves all three objectives. The core idea of CATCHUp is to store paths instead of travel times at shortcuts. Shortcut travel times are derived lazily from the stored paths. We perform an experimental study on a set of real world instances and compare our approach with state-of-the-art techniques. Our approach achieves the fastest preprocessing, competitive query running times and up to 30 times smaller indexes than competing approaches
STRASSER (Todd), La Vague
Get PDFIl y a maintenant longtemps que la question de l’enseignement de la Shoah constitue un sujet d’interrogation et de débat. L’Allemagne fédérale, Israël et les États-Unis ont connu des réflexions nombreuses sur la manière de faire en sorte que, grâce à l’école, l’histoire ne puisse se répéter, suivant la formule consacrée. L’ouvrage de Todd Strasser, qui est la version romancée d’une histoire réellement vécue dans un lycée américain au cours des années 1970, en est l’illustration. Ben Ross est ..
Weisheit von Sirach
No full text"Ben Sira, wisdom of (also called Ecclesiasticus), a work of the Apocrypha, which, though usually known by this name, may have been called by its author, "The Words of Simeon b. Jeshua," the title found on the Hebrew fragments" (Encyc. Judaica, CD-Rom Ed., 1997)Erscheinungsjahr nach Vorlage: 279 [i.e. 1519]Ben Sira folgen noch eine Reihe anderer Abhandlungen cf. Steinschneider p. 203 No. 1363. Die wichtigsten NZ!Siehe auch Karl Heinz Burmeister, Sebastian Münster, in: Basler Beiträge zur Geschichtswissenschaft, Bd. 91, 1963, S. 8
Delay-Robust Journeys in Timetable Networks with Minimum Expected Arrival Time
Get PDFWe study the problem of computing delay-robust routes in timetable
networks. Instead of a single path we compute a decision graph containing all stops and trains/vehicles that might be relevant. Delays are formalized using a stochastic model. We show how to compute a decision graph that minimizes the expected arrival time while bounding the latest arrival time over all sub-paths. Finally we show how the information contained within a decision graph can compactly be represented to the user. We experimentally evaluate our algorithms and show that the running times allow for interactive usage on a realistic train network
Autoworker and acclaimed author Ben Hamper speaks at the Michigan Writers Series
No full textIn an appearance at the Michigan State University Main Library, autoworker and acclaimed author Ben Hamper talks about his career at the General Motors Truck and Bus Plant in Flint, Michigan and reads from various works, including his forward to the book "Working words: punching the clock and kicking out the jams" by M. L. Liebler and from his most famous work, "Rivethead", a cynical and humorous view of life in an auto plant. A question and answer session follows. Hamper is introduced by Michigan State University Professor John P. Beck for the Michigan State University Libraries' Michigan Writers Series
Martin Loughlin, Public Law and Political Theory
No full textIn this chapter, Ben Yong discusses Martin Loughlin’s Public Law and Political Theory. Drawing in part on conversation with the author, Yong explores the significance of a book that, despite interrogating the nature of public law as a discipline in a novel and methodologically important way, is often poorly understood
Idan Ben-Barak: Cook Prize 2024, Silver Medal Acceptance Speech.
No full textAuthor Idan Ben-Barak gives an acceptance speech for We Go Way Back (Roaring Brook Press)https://educate.bankstreet.edu/cook/1010/thumbnail.jp
- …
