Ziadi, Djelloul Regular expression for a language without empty word. (English) Zbl 0878.68080 Theor. Comput. Sci. 163, No. 1-2, 309-315 (1996). Summary: A. Brüggemann-Klein [ibid. 120, No. 2, 197-213 (1993; Zbl 0811.68096)] asks the following question: “Is there a linear-time algorithm transforming a regular expression \(E\) into an expression \(E^-\) with \({\mathcal L}_{E^-}={\mathcal L}_E\backslash\{\varepsilon\}\)?” In this paper, we give a recursive definition of \(E^-\) which enables us to provide such an algorithm. Furthermore, we show that \[ |E^-|\leq {|E|+1\over 2}\log(|E|+ 1)+ {|E|-1\over 2}, \] where \(|E|\) is the size of \(E\), and \(|E^-|\) is the size of \(E^-\). Cited in 6 Documents MSC: 68Q45 Formal languages and automata Citations:Zbl 0811.68096 PDFBibTeX XMLCite \textit{D. Ziadi}, Theor. Comput. Sci. 163, No. 1--2, 309--315 (1996; Zbl 0878.68080) Full Text: DOI References: [1] Brüggemann-Klein, A., Regular expressions into finite automata, Theoret. Comput. Sci., 120, 197-213 (1993) · Zbl 0811.68096 This reference list is based on information provided by the publisher or from digital mathematics libraries. Its items are heuristically matched to zbMATH identifiers and may contain data conversion errors. In some cases that data have been complemented/enhanced by data from zbMATH Open. This attempts to reflect the references listed in the original paper as accurately as possible without claiming completeness or a perfect matching.