• Publications
  • Influence
Embedding Brouwer Algebras in the Medvedev Lattice
  • A. Sorbi
  • Mathematics, Computer Science
  • Notre Dame J. Formal Log.
  • 19 March 1991
  • 22
  • 5
Classifying Positive Equivalence Relations
  • 54
  • 4
Some Remarks on the Algebraic Structure of the Medvedev Lattice
  • A. Sorbi
  • Mathematics, Computer Science
  • J. Symb. Log.
  • 1 June 1990
TLDR
This paper investigates the algebraic structure of the Medvedev lattice . Expand
  • 30
  • 3
A Survey on Universal Computably Enumerable Equivalence Relations
TLDR
We review the literature on universal computably enumerable equivalence relations (ceers) which are \(\Sigma ^0_1\)-complete with respect to computable reducibility on equivalence relation. Expand
  • 19
  • 3
  • PDF
Generalized computable numerations and nontrivial rogers semilattices
We outline the general approach to the notion of a computable numeration in the frames of which computable numerations, of families of arithmetic sets are studied.
  • 55
  • 3
New Computational Paradigms: Changing Conceptions of What is Computable
TLDR
In recent years, classical computability has expanded beyond its original scope to address issues related to computability and complexity in algebra, analysis, and physics. Expand
  • 100
  • 2
Cupping and Noncupping in the Enumeration Degrees of Sigma20 Sets
TLDR
We prove the following three theorems on the enumeration degrees of ∑ 2 0 sets with the anticupping property . Expand
  • 26
  • 2
  • PDF
Intermediate logics and factors of the Medvedev lattice
TLDR
We investigate the initial segments of the Medvedev lattice as Brouwer algebras, and study the propositional logics connected to them. Expand
  • 18
  • 2
  • PDF
The Medvedev lattice of degrees of difficulty
TLDR
Mass problems correspond to informal problems in the following sense: given any informal problem, a mass problem corresponding to it is a set of functions which "solve" the problem, and at least one such function can be "obtained" by any "solution" to the problem. Expand
  • 19
  • 2
Joins and meets in the structure of ceers
TLDR
We study computably enumerable equivalence relations (abbreviated as ceers) under computable reducibility, and investigate the resulting degree structure Ceers, which is a poset with a smallest and a greatest element. Expand
  • 18
  • 2
  • PDF