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Abstract:
We apply a non-classical four-valued logic in the process of reasoning regarding strategies for cops in a modified game of "Cops and Robber" played on a graph. We extend the game by introducing uncertainty in a form of random failures of detecting devices. This is realized by allowing that a robber can be detected in a node only with the given probability PA. Additionally, with the probability PF, cops can be given a false-positive, i.e., they are informed that the robber is located at some node, whereas it is located somewhere else. Consequently, non-zero PF introduces a measurement noise into the system. All the cops have access to information provided by the detectors and can communicate with each other, so they can coordinate the search. By adjusting the number of detectors, PA, and PF we can achieve a smooth transition between the two well-known variants of the game: "with fully visible robber" and "with invisible robber". We compare a simple probabilistic strategy for cops with the non-parametric strategy based on reasoning with a four-valued paraconsistent logic. It is shown that this novel approach leads to a good performance, as measured by the required mean catch-time. We conclude that this type of reasoning can be applied in real-world applications where there is no knowledge about the underlying source of errors which is particularly useful in robotics.

Keywords:
reasoning under uncertainty, non-classical logics, four-valued logic, paraconsistent reasoning, cops and robber game, multi-robotic systems

Abstract:
The paper reports initial results on modeling and simulating cooperation of rescue robots. Our aim is to investigate the efficiency of the “first simulate then act” paradigm for rescue operations undertaken by multiple mobile robots, assuming that information about the environment can be incomplete and partially inconsistent. To deal with ignorance and contradictions we adopt a non–standard logic in the inference engine. To demonstrate feasibility of our approach we present the architecture of the developed simulator and results of experiments done so far.

Keywords:
four-valued logic, search and rescue, multirobotic systems