Combinatorial Properties and Recognition of Unit Square Visibility Graphs *

Katrin Casel, Henning Fernau, Alexander Grigoriev, Markus Schmid, Sue Whitesides
Unit square (grid) visibility graphs (USV and USGV, resp.) are described by axis-parallel visibility between unit squares placed (on integer grid coordinates) in the plane. We investigate combinatorial properties of these graph classes and the hardness of variants of the recognition problem, i. e., the problem of representing USGV with fixed visibilities within small area and, for USV, the general recognition problem.