
Mathematics 2012
Ambiguity of ωLanguages of Turing MachinesDOI: 10.2168/LMCS10(3:12)2014 Abstract: An {\omega}language is a set of infinite words over a finite alphabet X. We consider the class of recursive {\omega}languages, i.e. the class of {\omega}languages accepted by Turing machines with a B\"uchi acceptance condition, which is also the class {\Sigma}11 of (effective) analytic subsets of X{\omega} for some finite alphabet X. We investigate here the notion of ambiguity for recursive {\omega}languages with regard to acceptance by B\"uchi Turing machines. We first present in detail essentials on the literature on {\omega}languages accepted by Turing Machines. Then we give a complete and broad view on the notion of ambiguity and unambiguity of B\"uchi Turing machines and of the {\omega}languages they accept. To obtain our new results, we make use of results and methods of effective descriptive set theory.
