NOTES ON DUAL CONCATENATION
Alexander Okhotin · International Journal of Foundations of Computer Science · 2007
It was recently found that concatenation of formal languages has a logical dual (A. Okhotin, The dual of concatenation, Theoret. Comput. Sci., 345 (2005), 425–447). In this paper, the closure or nonclosure of common language families under dual concatenation with finite, co-finite and regular languages is determined. In addition, language equations with union, linear concatenation and dual concatenation with co-finite constants are shown to be almost equal in power to linear conjunctive grammars.