ISSN 1364-0380 (on line) 1465-3060 (printed) 1 eometry & opology G T G T Volume 9 (2005) 1–93 GG T T T G T G T Published: 17 December 2004 G T G T T G T G T G T G T G G G G T T Monopoles over 4–manifolds containing long necks, I Kim A Frøyshov Fakult¨at f¨ur Mathematik, Universit¨at Bielefeld Postfach 100131, D-33501 Bielefeld, Germany Email:
[email protected] Abstract We study moduli spaces of Seiberg–Witten monopoles over spinc Riemannian 4–manifolds with long necks and/or tubular ends. This first part discusses compactness, exponential decay, and transversality. As applications we prove two vanishing theorems for Seiberg–Witten invariants. AMS Classification numbers Primary: 57R58 Secondary: 57R57 Keywords: Floer homology, Seiberg–Witten, Bauer–Furuta, compactness, monopoles Proposed:DieterKotschick Received:9October2003 Seconded: Simon Donaldson, Tomasz Mrowka Revised: 1 December 2004 c eometry & opology ublications G T P 2 Kim A Frøyshov 1 Introduction This is the first of two papers devoted to the study of moduli spaces of Seiberg– Witten monopoles over spinc Riemannian 4–manifolds with long necks and/or tubular ends. Our principal motivation is to provide the analytical foundations for subsequent work on Floer homology. Such homology groups should appear naturally when one attempts to express the Seiberg–Witten invariants of a closed spinc 4–manifold Z cut along a hypersurface Y , say Z = Z Z , 1 ∪Y 2 in terms of relative invariants of the two pieces Z1,Z2 . The standard approach, familiar from instanton Floer theory (see [13, 10]), is to construct a 1–parameter family g of Riemannian metrics on Z by stretching along Y so as to obtain { T } a neck [ T, T ] Y , and study the monopole moduli space M (T ) over (Z, g ) − × T for large T .