In this paper, we propose the notion of +unambiguous product which is expanded from unambiguous product and the definitions of alternative product, alternative code, even alternative code on a pair (X, Y) of languages. Some basic properties of +unambiguous product, alternative codes and even alternative codes related to usual codes are given which show that these new codes can be considered as generations of codes. Necessary and sufficient conditions for alternative codes and even alternative codes are established. The independence of the claims in these conditions are proved. The existence of algorithms to decide whether a pair (X, Y) is an alternative or is an even alternative code, in case both components X, Y are regular, is shown. © 2010 Springer-Verlag Berlin Heidelberg.

Vinh H.N., Nam V.T., Huy P.T.

47.pdf    Gửi cho bạn bè

Từ khóa : +unambiguous product; Alt-code; Ealt-code; Generations of code; Independency of conditions