Cancellation in the Stone–Čech compactification of a discrete semigroup
Neil Hindman, Dona Strauss · Proceedings of the Edinburgh Mathematical Society · 1994
We investigate both left and right cancellation in the Stone–Čech compactification βSof a discrete semigroupS, obtaining several results for arbitrary semigroupsSand others for more restricted semigroups. In particular, ifSis the semigroup of injective functions from a set to itself we determine precisely which pairsx, yandShave somep∈βSwithpx=py. We also obtain several new results about right cancellation in (βℕ, +).