Covering Maps and Discontinuous Group Actions
... (iii) given any point x of X, there exists an open set U in X such that x ∈ U and θg (U ) ∩ U = ∅ for all g ∈ G satisfying g 6= e. Let G be a group which acts freely and properly discontinuously on a topological space X. Given any element g of G, the corresponding continuous function θg : X → X dete ...
... (iii) given any point x of X, there exists an open set U in X such that x ∈ U and θg (U ) ∩ U = ∅ for all g ∈ G satisfying g 6= e. Let G be a group which acts freely and properly discontinuously on a topological space X. Given any element g of G, the corresponding continuous function θg : X → X dete ...
On topological models of GLP
... outside this class due to the presence of Löb’s axiom which contradicts reflection. For these logics one takes a different approach that reads ! as the derived set operator d mapping a set A to the set of limit points of A. The study of this interpretation was suggested in the Appendix of [25], and ...
... outside this class due to the presence of Löb’s axiom which contradicts reflection. For these logics one takes a different approach that reads ! as the derived set operator d mapping a set A to the set of limit points of A. The study of this interpretation was suggested in the Appendix of [25], and ...
