|
We prove a generalization of Bennequin’s inequality for Legendrian knots in a
3-dimensional contact manifold (Y,ξ), under the assumption that Y is the boundary
of a 4-dimensional manifold M and the version of Seiberg-Witten invariants
introduced by Kronheimer and Mrowka [Invent. Math. 130 (1997) 209–255] is
nonvanishing. The proof requires an excision result for Seiberg-Witten moduli spaces;
then the Bennequin inequality becomes a special case of the adjunction inequality for
surfaces lying inside M.
|