Krenn, DanielShallit, Jeffrey2022-01-252022-01-252020-05https://doi.org/10.1016/j.tcs.2022.01.018http://hdl.handle.net/10012/17966In this paper we consider a number of natural decision problems involving k-regular sequences. Specifically, they arise from considering • lower and upper bounds on growth rate; in particular boundedness, • images, • regularity (recognizability by a deterministic finite automaton) of preimages, and • factors, such as squares and palindromes, of such sequences. We show that these decision problems are undecidable.enk-regular sequencedecidabilityunsolvabilityArticle