## Algebraic & Geometric Topology

### More Cappell–Shaneson spheres are standard

Robert E Gompf

#### Abstract

Akbulut has recently shown that an infinite family of Cappell–Shaneson homotopy $4$–spheres is diffeomorphic to the standard $4$–sphere. In the present paper, a different method shows that a strictly larger family is standard. This new approach uses no Kirby calculus except through the relatively simple 1979 paper of Akbulut and Kirby showing that the simplest example with untwisted framing is standard. Instead, hidden symmetries of the original Cappell–Shaneson construction are exploited. In the course of the proof, an example is given showing that Gluck twists can sometimes be undone using symmetries of fishtail neighborhoods.

#### Article information

Source
Algebr. Geom. Topol., Volume 10, Number 3 (2010), 1665-1681.

Dates
Revised: 5 June 2010
Accepted: 8 June 2010
First available in Project Euclid: 19 December 2017

https://projecteuclid.org/euclid.agt/1513715148

Digital Object Identifier
doi:10.2140/agt.2010.10.1665

Mathematical Reviews number (MathSciNet)
MR2683748

Zentralblatt MATH identifier
1244.57061

Subjects
Primary: 57R60: Homotopy spheres, Poincaré conjecture

#### Citation

Gompf, Robert E. More Cappell–Shaneson spheres are standard. Algebr. Geom. Topol. 10 (2010), no. 3, 1665--1681. doi:10.2140/agt.2010.10.1665. https://projecteuclid.org/euclid.agt/1513715148

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