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Journal for Geometry and Graphics 22 (2018), No. 1, 031--039 Copyright Heldermann Verlag 2018 Classification and Normal Forms of Planar 4-Multisets and Quadrangles Peteris Daugulis Daugavpils University, Parades 1, Daugavpils 5400, Latvia peteris.daugulis@du.lv This article is devoted to the problem of describing similarity types of geometric objects. We give a solution of this problem for the case of four points in plane. The general case is subdivided into several subcases depending on configurations of points in maximum distance. Similarity types are parametrized by a point or a pair of points in the plane. Keywords: Normal forms, similarity, quadrangle. MSC: 51M04; 51N20, 97G50 [ Fulltext-pdf (286 KB)] |