Unobstructed Immersed Lagrangian Correspondence and Filtered $A_{\infty}$ Functor
Kenji Fukaya
TL;DR
This work establishes a comprehensive 2-categorical framework connecting unobstructed immersed Lagrangian Floer theory with filtered $A_{ obreak ext{∞}}$ categories. It constructs a 2-functor from the unobstructed immersed Weinstein category to the 2-category of all strict, unital filtered $A_{ obreak ext{∞}}$ categories, using immersed Lagrangian correspondences with bounding cochains and Yoneda-type representability. A key innovation is the algebraic–geometric bridge via Künneth bi-functors and tri-modules, realized through quilted moduli spaces, and the use of Lekili–Lipyanskiy’s Y-diagram to prove compatibility and associativity results without relying on strip shrinking or Figure-8 bubbles. The results generalize prior work (Wehrheim–Woodward, Mau–Wehrheim–Woodward) to complete compact settings, providing a robust foundation for composing and representing Lagrangian correspondences in the immersed setting, with potential applications to gauge theory and beyond. The paper also develops the obstruction theory via bounding cochains, guaranteeing unobstructedness under geometric transformations and establishing a coherent functorial calculus for immersed Lagrangian Floer theory.
Abstract
In this paper, we 'construct' a 2-functor from the unobstructed immersed Weinstein category to the category of all filtered $A_{\infty}$ categories. We consider arbitrary (compact) symplectic manifolds and its arbitrary (relatively spin) immersed Lagrangian submanifolds. The filtered $A_{\infty}$ category associated to $(X,ω)$ is defined by using Lagrangian Floer theory in such generality, see Akaho-Joyce (2010) and Fukaya-Oh-Ohta-Ono (2009). The morphism of unobstructed immersed Weinstein category (from $(X_1,ω_1)$ to $(X_2,ω_2)$) is by definition a pair of an immersed Lagrangian submanifold of the direct product and its bounding cochain (in the sense of Akaho-Joyce (2010) and Fukaya-Oh-Ohta-Ono (2009)). Such a morphism transforms an (immersed) Lagrangian submanifold of $(X_1,ω_1)$ to one of $(X_2,ω_2)$. The key new result proved in this paper shows that this geometric transformation preserves unobstructedness of the Lagrangian Floer theory. Thus, this paper generalizes earlier results by Wehrheim-Woodward and Mau's-Wehrheim-Woodward so that it works in complete generality in the compact case. The main idea of the proofs are based on Lekili-Lipyanskiy's Y diagram and a lemma from homological algebra, together with systematic use of Yoneda functor. In other words, the proofs are based on a different idea from those which are studied by Bottmann-Mau's-Wehrheim-Woodward, where strip shrinking and figure 8 bubble plays the central role.
