Let r be a fixed positive integer. It is shown that, given any partial orders >1, . . ., >r on the same n-element set P, there exist disjoint subsets A, B P, each with at l...
We introduce the notion of an unrefinable decomposition of a 1-design with at most two block intersection numbers, which is a certain decomposition of the 1-designs collection of ...
Assume that two points p and q are given and a finite ordered set of simple polygons, all in the same plane; the basic version of a touring-a-sequence-of-polygons problem (TPP) is...