Gerhard Trippen

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How efficiently can we search an unknown environment for a goal in unknown position? How much would it help if the environment were known? We answer these questions for simple polygons and for general graphs, by providing online search strategies that are as good as the best offline search algorithms, up to a constant factor. For other settings we prove(More)
This video shows the problem of localization. A robot has to nd its position on a map, in our case a geometric tree of bounded degree. The strategy LPS (Localize-by-Placement-Separation) is known to guarantee that the distance traveled by the robot is at most O(p n) times longer than the shortest possible route to localize the robot, where n is the number(More)
We consider the problem of a searcher that looks, for example, for a lost flashlight in a dusty environment. The search agent finds the flashlight as soon as it crosses the ray emanating from the flashlight, and in order to pick it up, the searcher has to move to the origin of the light beam. First, we give a search strategy for a special case of the ray(More)
We define simple-regular expressions and languages. Simple-regular languages provide a necessary condition for a language to be outfix-free. We design algorithms that compute simple-regular languages from finite-state automata. Furthermore, we investigate the complexity blowup from a given finite-state automaton to its simple-regular language automaton and(More)