#### Geometry & Topology Monographs 2 (1999),
Proceedings of the Kirbyfest,
paper no. 23, pages 473-488.

## A polynomial invariant of diffeomorphisms of 4-manifolds

### Daniel Ruberman

**Abstract**.
We use a 1-parameter version of gauge theory to investigate the
topology of the diffeomorphism group of 4-manifolds. A polynomial
invariant, analogous to the Donaldson polynomial, is defined, and is
used to show that the diffeomorphism group of certain simply-connected
4-manifolds has infinitely generated \pi _0.
**Keywords**.
Diffeomorphism, isotopy, 4-manifold

**AMS subject classification**.
Primary: 57R52. Secondary: 57R57.

**E-print:** `arXiv:math.GT/9911260`

Submitted: 14 October 1999.
(Revised: 18 November 1999.)
Published: 23 November 1999.

Notes on file formats
Daniel Ruberman

Department of Mathematics, Brandeis University

Waltham, MA 02254, USA

Email: ruberman@binah.cc.brandeis.edu

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