Proceedings of the 8th Cologne-Twente Workshop on Graphs and Combinatorial Optimization

International audienceThe Cologne-Twente Workshop (CTW) on Graphs and Combinatorial Optimization started off as a series of workshops organized bi-annually by either Köln University or Twente University. As its importance grew over time, it re-centered its geographical focus by including northern Italy (CTW04 in Menaggio, on the lake Como and CTW08 in Gargnano, on the Garda lake). This year, CTW (in its eighth edition) will be staged in France for the first time: more precisely in the heart of Paris, at the Conservatoire National d’Arts et Métiers (CNAM), between 2nd and 4th June 2009, by a mixed organizing committee with members from LIX, Ecole Polytechnique and CEDRIC, CNAM

Winona Daily News

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The perfection and recognition of bull-reducible Berge graphs

The recently announced Strong Perfect Graph Theorem states that the class of perfect graphs coincides with the class of graphs containing no induced odd cycle of length at least 5 or the complement of such a cycle. A graph in this second class is called Berge. A bull is a graph with five vertices x, a, b, c, d and five edges xa, xb, ab, ad, bc. A graph is bull-reducible if no vertex is in two bulls. In this paper we give a simple proof that every bull-reducible Berge graph is perfect. Although this result follows directly from the Strong Perfect Graph Theorem, our proof leads to a recognition algorithm for this new class of perfect graphs whose complexity, O(n6), is much lower than that announced for perfect graphs

The Papers of Thomas A. Edison

This richly illustrated volume explores Edison’s inventive and personal pursuits from 1885 to 1887.Two decades after the American Civil War, no name was more closely associated with the nation’s inventive and entrepreneurial spirit than that of Thomas Edison. The restless changes of those years were reflected in the life of America’s foremost inventor. Having cemented his reputation with his electric lighting system, Edison had decided to withdraw partially from that field. At the start of 1885, newly widowed at mid-life with three young children, he launched into a series of personal and professional migrations, setting in motion chains of events that would influence his work and fundamentally reshape his life. Edison’s inventive activities took off in new directions, flowing between practical projects (such as wireless and high-capacity telegraph systems) and futuristic ones (exploring forms of electromagnetic energy and the convertibility of one to another). Inside of two years, he would travel widely, marry the daughter of a prominent industrialist and religious educator, leave New York City for a grand home in a sylvan suburb, and construct a winter laboratory and second home in Florida. Edison’s family and interior life are remarkably visible at this moment; his papers include the only known diary in which he recorded personal thoughts and events. By 1887, the familiar rhythms of his life began to reassert themselves in his new settings; the family faded from view as he planned, built, and occupied a New Jersey laboratory complex befitting his status. The eighth volume of the series, New Beginnings includes 358 documents (chosen from among thousands) that are the most revealing and representative of Edison’s work, life, and place in American culture in these years. Illustrated with hundreds of Edison’s drawings, these documents are further illuminated by meticulous research on a wide range of sources, including the most recently digitized newspapers and journals of the day

The Papers of Thomas A. Edison

This richly illustrated volume explores Edison's inventive and personal pursuits from 1888 to 1889, documenting his responses to technological, organizational, and economic challenges.Thomas A. Edison was received at the 1889 Paris Exposition Universelle—the World's Fair—as a conquering hero. Extravagantly fêted and besieged by well-wishers, he was seen, like Gustave Eiffel's iron tower, as a triumphal symbol of republicanism and material progress. The visit was a high-water mark of his international fame.Out of the limelight, Edison worked as hard as ever. On top of his work as an inventor, entrepreneur, and manufacturer, he created a new role as a director of research. At his peerless laboratory in Orange, New Jersey, he directed assistants working in parallel on multiple projects. These included the "perfected" phonograph; a major but little-recognized effort to make musical recordings for sale; the start of work on motion pictures; and improvements in the recovery of low-grade iron ore. He also pursued a public "War of the Currents" against electrical rival George Westinghouse. Keenly attuned to manufacturing as a way to support the laboratory financially and control his most iconic products, Edison created a new cluster of factories. He kept his manufacturing rights to the phonograph while selling the underlying patents to an outside investor in a deal he would regret. When market pressures led to the consolidation of Edison lighting interests, he sold his factories to the new Edison General Electric Company. These changes disrupted his longtime personal and professional relations even as he planned an iron-mining project that would take him to the New Jersey wilderness for long periods.The ninth volume of the series, Competing Interests explores Edison's inventive and personal pursuits from 1888 to 1889, documenting his responses to technological, organizational, and economic challenges. The book includes 331 documents and hundreds of Edison's drawings, which are all revealing and representative of his life and work in these years. Essays and notes based on meticulous research in a wide range of sources, many only recently available, provide a rich context for the documents