Reducibilities among equivalence relations induced by recursively enumerable structures
نویسندگان
چکیده
In this paper we investigate the dependence of recursively enumerable structures on the equality relation which is fixed to a specific r.e. equivalence relation. We compare r.e. equivalence relations on the natural numbers with respect to the amount of structures they permit to represent from a given class of structures such as algebras, permutations and linear orders. In particular, we show that for various types of structures represented, there are minimal and maximal elements.
منابع مشابه
Computably Enumerable Equivalence Relations
We study computably enumerable equivalence relations (ceers) on N and unravel a rich structural theory for a strong notion of reducibility among ceers.
متن کاملEquivalence Relations That Are Σ03 Complete for Computable Reducibility - (Extended Abstract)
Let E,F be equivalence relations on N. We say that E is computably reducible to F , written E ≤ F , if there is a computable function p : N→ N such that xEy ↔ p(x)Fp(y). We show that several natural Σ 3 equivalence relations are in fact Σ 3 complete for this reducibility. Firstly, we show that one-one equivalence of computably enumerable sets, as an equivalence relation on indices, is Σ 3 compl...
متن کاملLinear Orders Realized by C.E. Equivalence Relations
Let E be a computably enumerable (c.e.) equivalence relation on the set ω of natural numbers. We say that the quotient set ω/E (or equivalently, the relation E) realizes a linearly ordered set L if there exists a c.e. relation E respecting E such that the induced structure (ω/E;E) is isomorphic to L. Thus, one can consider the class of all linearly ordered sets that are realized by ω/E; formall...
متن کاملGraphs realised by r.e. equivalence relations
We investigate dependence of recursively enumerable graphs on the equality relation given by a specific r.e. equivalence relation on ω. In particular we compare r.e. equivalence relations in terms of graphs they permit to represent. This defines partially ordered sets that depend on classes of graphs under consideration. We investigate some algebraic properties of these partially ordered sets. ...
متن کاملIntrinsic Complexity of Partial Learning
A partial learner in the limit [16], given a representation of the target language (a text), outputs a sequence of conjectures, where one correct conjecture appears infinitely many times and other conjectures each appear a finite number of times. Following [5] and [14], we define intrinsic complexity of partial learning, based on reducibilities between learning problems. Although the whole clas...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Theor. Comput. Sci.
دوره 612 شماره
صفحات -
تاریخ انتشار 2016