A Leray–Serre spectral sequence for Lagrangian Floer theory

Abstract

We consider symplectic fibrations as in Guillemin and Sternberg (J. Funct. Anal. 52 (1983) 106–128) and derive a spectral sequence to compute the Floer cohomology of certain fibered Lagrangians sitting inside a compact symplectic fibration with small monotone fibers and a rational base. We show that if the Floer cohomology with field coefficients of the fibered Lagrangian vanishes, then the Floer cohomology with field coefficients of the total Lagrangian also vanishes. We give an application to certain nontorus fibers of the Gelfand–Cetlin system in flag manifolds, and show that their Floer cohomology vanishes.