2015/07/06 by David Cook, David Cook II, Cook, David +2
Computer Science · Mathematics · #05A15 #05A19 #05B45 #Advanced Combinatorial Mathematics #Advanced Mathematical Identities #Algorithms and Data Compression #Combinatorics (math.CO) #FOS: Mathematics #math.CO #msc:05A15 #msc:05A19 #msc:05B45
paper · pdf · doi:10.48550/arxiv.1507.02507
23 pages. formerly part of arXiv:1305.1314
arxiv created 2015/07/06 · openalex publication_date 2015/07/06 · arxiv updated 2015/07/10 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
It is well-known that plane partitions, lozenge tilings of a hexagon, perfect matchings on a honeycomb graph, and families of non-intersecting lattice paths in a hexagon are all in bijection. In this work we consider regions that are more general than hexagons. They are obtained by further removing upward-pointing triangles. We call the resulting shapes triangular regions. We establish signed versions of the latter three bijections for triangular regions. We first investigate the tileability of triangular regions by lozenges. Then we use perfect matchings and families of non-intersecting lattice paths to define two signs of a lozenge tiling. Using a new method that we call resolution of a puncture, we show that the two signs are in fact equivalent. As a consequence, we obtain the equality of determinants, up to sign, that enumerate signed perfect matchings and signed families of lattice paths of a triangular region, respectively. We also describe triangular regions, for which the signed enumerations agree with the unsigned enumerations.