-------- Original Message -------- Subject: [i-prof] Approximative Computations on Spanning Trees with Low Crossing Number: Verteidigung meiner Masterarbeit / Defense of my master thesis Date: Wed, 24 Jul 2013 10:07:58 +0200 From: Maximilian Konzack <maximilian.konzack@fu-berlin.de> To: i-profs@inf.fu-berlin.de, i-wimis@inf.fu-berlin.de, i-studi@inf.fu-berlin.de, renee.zentiks@fu-berlin.de Sehr geehrte Damen und Herren, auch ich will mein Studium beenden, deshalb lade ich Sie herzlich zur Verteidigung meiner Masterarbeit ein. Dear Sir or Madam, I am pleased to invite you to the defense of my master thesis. Datum / Date: Dienstag/Tuesday, 30.07.13 Raum / Room: SR 055 (Takustr. 9) Zeit / Time: 12:00 Uhr (s.t.) Betreuer / Supervisors: Prof. Dr. Wolfgang Mulzer Dr. Panos Giannopoulos Zusammenfassung / Abstract: On undirected and complete graphs having n points and a set of lines, the crossing number is the maximum number of intersections with a line for a spanning tree. Spanning Tree with Low Crossing Number (STLCN) is an optimization problem to minimize the crossing number. The computation of STLCN is assumed to be NP-hard. The aim of this study was to investigate the current approximations for STLCN and to revise some of their drawbacks. In this master thesis a new approximation was established using connected components in LP solving. Another aim was to evaluate the quality of the approximations on the crossing number in a computation study. Therefore, a comprehensive Python library for STLCN was developed. The experiments on most settings confirm a crossing number of O(sqrt(n)) which is consistent with the theory proving the existence of such a spanning tree. The proposed approximation compares well with the others. The iterative reweighting method, an widely applied meta method used for instance in the AdaBoost algorithm within the field of machine learning, is able to compute spanning trees with significantly fewer crossings. The evaluation of the computations indicates that optimizing STLCN leads to an average crossing number of O(log(n)). These results suggest that the crossing number may be approximated more tightly than expected. Those experiments on STLCN were applied ranging from artificial data sets to real data points from TSPLIB. Mit freundlichen Grüßen, / Kind regards, Maximilian Konzack _______________________________________________ Automatischer Mailverteiler an Gruppe 'ml-i-prof-mi'. Hinweise dazu siehe Hilfeseite: https://www.mi.fu-berlin.de/w/Tec/AnkuendigungsVerteiler
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