Enumeration of rhombus tilings of a hexagon which contain a fixed rhombus in the centre

摘要

We compute the number of rhombus tilings of a hexagon with side lengths a, h, c, a, b, c which contain the central rhombus and the number of rhombus tilings of a hexagon with side lengths a, b. c, a. b, c which contain the "almost central" rhombus above the centre. (C) 2001 Academic Press. [References: 13]