On Tilings by Ribbon Tetrominoes
Roman Muchnik, Igor Pak · Journal of Combinatorial Theory Series A · 1999
Introduction A ribbon polyomino is a polyomino which has at most one square (i; j) in every diagonal i \\Gamma j = c. A tetromino is a polyomino with four squares. Up to translations there are exactly 8 different ribbon tetrominoes, which we denote by 1 ; : : : ; 8 as in Fig. 1. Let T = f 1 ; : : : ; 8 g. 1 = 2 = 3 = 4 = 5 = 6 = 7 = 8 = Fig. 1 Now let \\Gamma be a simply connected region (a finite connected set of squares), and let be a tiling of \\Gamma by ribbon tetrominoes. This means that \\Gamma is covered 1 without intersection by parallel translations of ribbon tetrominoes.