Skip to Main Content

Transactions of the American Mathematical Society

Published by the American Mathematical Society since 1900, Transactions of the American Mathematical Society is devoted to longer research articles in all areas of pure and applied mathematics.

ISSN 1088-6850 (online) ISSN 0002-9947 (print)

The 2020 MCQ for Transactions of the American Mathematical Society is 1.48.

What is MCQ? The Mathematical Citation Quotient (MCQ) measures journal impact by looking at citations over a five-year period. Subscribers to MathSciNet may click through for more detailed information.


Ranked structures and arithmetic transfinite recursion
HTML articles powered by AMS MathViewer

by Noam Greenberg and Antonio Montalbán PDF
Trans. Amer. Math. Soc. 360 (2008), 1265-1307 Request permission


$\mathsf {ATR}_0$ is the natural subsystem of second-order arithmetic in which one can develop a decent theory of ordinals. We investigate classes of structures which are in a sense the “well-founded part" of a larger, simpler class, for example, superatomic Boolean algebras (within the class of all Boolean algebras). The other classes we study are: well-founded trees, reduced Abelian $p$-groups, and countable, compact topological spaces. Using computable reductions between these classes, we show that Arithmetic Transfinite Recursion is the natural system for working with them: natural statements (such as comparability of structures in the class) are equivalent to $\mathsf {ATR}_0$. The reductions themselves are also objects of interest.
Similar Articles
Additional Information
  • Noam Greenberg
  • Affiliation: Department of Mathematics, Notre Dame University, Notre Dame, Indiana 46556
  • Address at time of publication: School of Mathematics, Statistics and Computer Science, Victoria University, Wellington, New Zealand
  • MR Author ID: 757288
  • ORCID: 0000-0003-2917-3848
  • Email:,
  • Antonio Montalbán
  • Affiliation: Department of Mathematics, University of Chicago, Chicago, Illinois 60637
  • Email:
  • Received by editor(s): August 29, 2005
  • Published electronically: October 23, 2007
  • Additional Notes: We would like to thank our advisor Richard A. Shore for introducing us to questions that are discussed in this paper and for many useful conversations. Both authors were partially supported by NSF Grant DMS-0100035. This paper is part of the second author’s doctoral thesis.
  • © Copyright 2007 American Mathematical Society
  • Journal: Trans. Amer. Math. Soc. 360 (2008), 1265-1307
  • MSC (2000): Primary 03F35, 03D45; Secondary 03C57, 03B30
  • DOI:
  • MathSciNet review: 2357696