@article { , title = {Orbits of primitive k-homogenous groups on (N − k)-partitions with applications to semigroups}, abstract = {© 2018 American Mathematical Society. The purpose of this paper is to advance our knowledge of two of the most classic and popular topics in transformation semigroups: automorphisms and the size of minimal generating sets. In order to do this, we examine the k-homogeneous permutation groups (those which act transitively on the subsets of size k of their domain X) where |X| = n and k < n/2. In the process we obtain, for k-homogeneous groups, results on the minimum numbers of generators, the numbers of orbits on k-partitions, and their normalizers in the symmetric group. As a sample result, we show that every finite 2-homogeneous group is 2-generated. Underlying our investigations on automorphisms of transformation semigroups is the following conjecture: If a transformation semigroup S contains singular maps and its group of units is a primitive group G of permutations, then its automorphisms are all induced (under conjugation) by the elements in the normalizer of G in the symmetric group. For the special case that S contains all constant maps, this conjecture was proved correct more than 40 years ago. In this paper, we prove that the conjecture also holds for the case of semigroups containing a map of rank 3 or less. The effort in establishing this result suggests that further improvements might be a great challenge. This problem and several additional ones on permutation groups, transformation semigroups, and computational algebra are proposed at the end of the paper.}, doi = {10.1090/tran/7274}, eissn = {1088-6850}, issn = {0002-9947}, issue = {1}, journal = {Transactions of the American Mathematical Society}, pages = {105-136}, publicationstatus = {Published}, publisher = {American Mathematical Society}, url = {https://hull-repository.worktribe.com/output/453260}, volume = {371}, keyword = {Lasers and Light Matter Interactions, Specialist Research - Other, Transformation semigroups, Regular semigroups, Permutation groups, Primitive groups, Homogeneous groups, Rank of semigroups, Automorphisms of semigroups}, year = {2018}, author = {Araújo, João and Bentz, Wolfram and Cameron, Peter J.} }