Hyperplane arrangements are very interesting combinatorial objects and many results can be found in the literature. For instance, several papers [1, 2, 6, 7] are concerned with the characteristic polynomials and the number of regions of a hyperplane arrangement. In his paper [9], Stanley reviewed various hyperplane arrangements raising interesting questions, one of which is related to the follo...

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usually both ends of a transformer winding are at the same side of the magnetic core. with this arrangement there are automaticaly the same number of the turns for each winding in both core windows next to the middle leg of a three phase three leg core type transformer. contrary to this arrangement it is possible to put the two ends of a winding at the different sides of the core. in this case ...