Decidable discriminator varieties from unary classes
نویسندگان
چکیده
منابع مشابه
Decidable discriminator varieties from unary classes
Let /C be a class of (universal) algebras of fixed type. /C* denotes the class obtained by augmenting each member of K, by the ternary discriminator function (/(x,y, z) = x if x / ?/, ^(x,x,z) = 2:), while V(/C*) is the closure of /C* under the formation of subalgebras, homomorphic images, and arbitrary Cartesian products. For example, the class of Boolean algebras is definitionally equivalent ...
متن کاملDecidable Discriminator Varieties from Unary Varieties
We determine precisely those locally finite varieties of unary algebras of finite type which, when augmented by a ternary discriminator, generate a variety with a decidable theory.
متن کاملDecidable discriminator varieties with lattice stalks
We determine those universal classes of lattices which generate a decidable discriminator variety when augmented by a ternary discriminator term. They are the locally finite universal classes whose finite members are almost homogeneous.
متن کاملUnary PCF is Decidable
We show that unary PCF, a very small fragment of Plotkin’s PCF [?], has a decidable observational pre-order, and that its fully abstract model is effectively presentable. This is in marked contrast to larger fragments, where corresponding results fail [?]. The techniques used are adaptions of those of Padovani [?], who applied them to the minimal model of the simply typed lambda calculus.
متن کاملDecidable Problems for Unary PFAs
Given a PFA A and a cut-point λ, the isolation problem asks if there is a bound > 0 such that the acceptance probability of every word is bounded away from λ by . In this paper we show that the isolation problem for PFAs with a unary input alphabet is (a) coNPcomplete, if the cut-point is 0 or 1, and (b) is in coNP and coNP-hard, if the cut-point is in (0, 1). We also show that the language con...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Transactions of the American Mathematical Society
سال: 1993
ISSN: 0002-9947,1088-6850
DOI: 10.1090/s0002-9947-1993-1085938-8