Generation of sutured manifolds
Yi Ni
TL;DR
The paper proves that the set of connected sutured manifolds with fixed boundary type $R_{\pm}(\gamma)\cong F$ is generated, via surgery triads, by the product sutured manifold $(F,\partial F)\times[0,1]$, extending folklore results and enabling Floer-theoretic applications. The authors develop a framework based on generalized sutured Heegaard splittings (GSHS) and a Heegaard complexity $HC(M,\gamma)$, and they implement an induction on $HC$ by performing framed surgeries along pairs of non-separating attaching curves (NSACs) and Dehn twists to produce lower-$HC$ instances. The core technical steps show that any non-product case yields a surgery triad $(M,M',M'')$ with $HC(M',\gamma')<HC(M,\gamma)$ or $HC(M'',\gamma'')<HC(M,\gamma)$, allowing the construction of generators from the product. The results have implications for the use of Floer exact triangles in low-dimensional topology and connect to finite-generation phenomena for bordered sutured manifolds, with folklore special cases for $F=D^2$ or $F=S^2$.
Abstract
Given a compact, oriented, connected surface $F$, we show that the set of connected sutured manifolds $(M,γ)$ with $R_{\pm}(γ)\cong F$ is generated by the product sutured manifold $(F,\partial F)\times[0,1]$ through surgery triads. This result has applications in Floer theories of $3$--manifolds. The special case when $F=D^2$ or $S^2$ has been a folklore theorem, which has already been used by experts before.
