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Journal Articles Discrete and Computational Geometry Year : 2012

Triangle Contact Representations and Duality

Abstract

A contact representation by triangles of a graph is a set of triangles in the plane such that two triangles intersect on at most one point, each triangle represents a vertex of the graph and two triangles intersects if and only if their corresponding vertices are adjacent. de Fraysseix, Ossona de Mendez and Rosenstiehl proved that every planar graph admits a contact representation by triangles. We strengthen this in terms of a simultaneous contact representation by triangles of a planar map and of its dual. A primal-dual contact representation by triangles of a planar map is a contact representation by triangles of the primal and a contact representation by triangles of the dual such that for every edge uv, bordering faces f and g, the intersection between the triangles corresponding to u and v is the same point as the intersection between the triangles corresponding to f and g. We prove that every 3-connected planar map admits a primal-dual contact representation by triangles. Moreover, the interiors of the triangles form a tiling of the triangle corresponding to the outer face and each contact point is a node of exactly three triangles. Then we show that these representations are in one-to-one correspondence with generalized Schnyder woods defined by Felsner for 3-connected planar maps.

Dates and versions

lirmm-00715024 , version 1 (06-07-2012)

Identifiers

Cite

Daniel Gonçalves, Benjamin Lévêque, Alexandre Pinlou. Triangle Contact Representations and Duality. Discrete and Computational Geometry, 2012, 48 (1), pp.239-254. ⟨10.1007/s00454-012-9400-1⟩. ⟨lirmm-00715024⟩
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