par Cardinal, Jean ;Ito, Hiro;Korman, Matias ;Langerman, Stefan
Référence Graphs and combinatorics, 29, 5, page (1221-1234)
Publication Publié, 2013-09
Article révisé par les pairs
Résumé : We define the Helly number of a polyomino P as the smallest number h such that the h-Helly property holds for the family of symmetric and translated copies of P on the integer grid. We prove the following: (i) the only polyominoes with Helly number 2 are the rectangles, (ii) there does not exist any polyomino with Helly number 3, (iii) there exist polyominoes of Helly number k for any k ≠ 1, 3. © 2012 Springer.