Inspired by classic work of Wallman and more recent work of Jung-Kegelmann-Moshier and Vickers , we show how to encode general subbases of stably locally compact spaces via certain entailment relations. We further build this up to a categorical duality encompassing the classic Priestley-Stone duality and its various extensions to stably locally compact spaces by Shirota, De Vries, Hofmann-Lawson (in the stable case), Jung-Sünderhauf, Hansoul-Poussart, Bezhanishvili-Jansana, van Gool and Bice-Starling.

Abstract We present three examples of countable homogeneous structures (also called Fraïssé limits ) whose automorphism groups are not universal, namely, fail to contain isomorphic copies of all automorphism groups of their substructures. Our first example is a particular case of a rather general construction on Fraïssé classes, which we call diversification , leading to automorphism groups containing copies of all finite groups. Our second example is a special case of another general construction on Fraïssé classes, the mixed sums , leading to a Fraïssé class with all finite symmetric groups appearing as automorphism groups and at the same time with a torsion-free automorphism group of its Fraïssé limit. Our last example is a Fraïssé class of finite models with arbitrarily large finite abelian automorphism groups, such that the automorphism group of its Fraïssé limit is again torsion-free.