9
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: found
      Is Open Access

      Calibrating word problems of groups via the complexity of equivalence relations

      Preprint
      ,

      Read this article at

      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          (1) There is a finitely presented group with a word problem which is a uniformly effectively inseparable equivalence relation. (2) There is a finitely generated group of computable permutations with a word problem which is a universal co-computably enumerable equivalence relation. (3) Each c.e. truth-table degree contains the word problem of a finitely generated group of computable permutations.

          Related collections

          Most cited references10

          • Record: found
          • Abstract: not found
          • Article: not found

          Subgroups of Finitely Presented Groups

          G. Higman (1961)
            Bookmark
            • Record: found
            • Abstract: not found
            • Article: not found

            Recursive Unsolvability of Group Theoretic Problems

              Bookmark
              • Record: found
              • Abstract: found
              • Article: not found

              Classifying positive equivalence relations

              Given two (positive) equivalence relations ~ 1 , ~ 2 on the set ω of natural numbers, we say that ~ 1 is m-reducible to ~ 2 if there exists a total recursive function h such that for every x, y ∈ ω , we have x ~ 1 y iff hx ~ 2 hy . We prove that the equivalence relation induced in ω by a positive precomplete numeration is complete with respect to this reducibility (and, moreover, a “uniformity property” holds). This result allows us to state a classification theorem for positive equivalence relations (Theorem 2). We show that there exist nonisomorphic positive equivalence relations which are complete with respect to the above reducibility; in particular, we discuss the provable equivalence of a strong enough theory: this relation is complete with respect to reducibility but it does not correspond to a precomplete numeration. From this fact we deduce that an equivalence relation on ω can be strongly represented by a formula (see Definition 8) iff it is positive. At last, we interpret the situation from a topological point of view. Among other things, we generalize a result of Visser by showing that the topological space corresponding to a partition in e.i. sets is irreducible and we prove that the set of equivalence classes of true sentences is dense in the Lindenbaum algebra of the theory.
                Bookmark

                Author and article information

                Journal
                2016-09-12
                Article
                1609.03371
                b1f7dd2b-f06a-4e8f-bb5c-819b1439572c

                http://arxiv.org/licenses/nonexclusive-distrib/1.0/

                History
                Custom metadata
                03D45
                13 pages
                math.LO

                Logic & Foundation
                Logic & Foundation

                Comments

                Comment on this article