Gutek, A.Moshokoa, S.P.Rajagopalan, M.Sundaresan, K.2025-01-072025-01-072011-01-010166-8641 (P)1879-3207 (E)https://doi.org/10.1016/j.topol.2011.05.042https://hdl.handle.net/20.500.14519/1103Let D be a countable discrete space and let p ∈ D. For any primitive shift σ : D → D \ {p} there are 2c σ-invariant maximal almost disjoint families on D. This implies that there are 2c pairwise non-homeomorphic Ψ∗ spaces admitting primitive shifts. Under a = c there exists a maximal almost disjoint family F on a countable discrete space D such that the spaces Ψ (F) and Ψ∗(F) admit no primitive shift.1715-1718 PagesenAttribution-NonCommercial-ShareAlike 4.0 Internationalhttp://creativecommons.org/licenses/by-nc-sa/4.0/Isometric shiftPrimitive shiftMaximal almost disjoint familyΨ-spaceΨ∗-spaceArticle