Protorus

In mathematics, a protorus is a compact connected topological abelian group. Equivalently, it is a projective limit of tori (products of a finite number of copies of the circle group), or the Pontryagin dual of a discrete torsion-free abelian group.

Some examples of protori are given by solenoid groups.

• Duocylinder - Cartesian product of two disks
• Proprism

• Hofmann, Karl H.; Morris, Sidney A. (2006), The structure of compact groups, de Gruyter Studies in Mathematics, vol. 25 (2nd ed.), Berlin: Walter de Gruyter & Co., ISBN 978-3-11-019006-9, MR 2261490