Generalized Regular Counting Classes

  • Authors:
  • Ulrich Hertrampf

  • Affiliations:
  • -

  • Venue:
  • MFCS '99 Proceedings of the 24th International Symposium on Mathematical Foundations of Computer Science
  • Year:
  • 1999

Quantified Score

Hi-index 0.00

Visualization

Abstract

Complexity classes, which are defined via finite commutative monoids, can be considered as (very) regular counting classes. These include well-known classes like NP, coNP, ⊕P, other MOD-classes, but also the classes of finite acceptance type, and many more. In these cases, the acceptance mechanism can be defined by a regular leaf language, where acceptance really depends only on the number of occurrences of the various letters in the actual leafstring. In other words, the acceptance mechanism is given by a symmetric regular language. Generally all classes described in this way are the so called eventually periodic counting classes. In this paper we relax the symmetry condition on the regular leaf language: We allow all regular leaf languages, but we admit only machines, which on all input words will only produce symmetric leafstrings, which means all appearing leaf strings will either under all permutations belong to the acceptance language, or under all permutations not belong to the acceptance language. We give an exact characterization of all complexity classes, which can be described in this manner. It turns out that besides the classes obtained via finite commutative monoids, we also can describe promise classes like UP or MODZ2P in this way.