Stable Morse flow trees
Kenneth Blakey
TL;DR
The paper proves a Floer-Gromov-type compactness theorem for (pre)stable Morse flow trees of Legendrians in 1-jet spaces with simple front singularities, under Ekholm's preliminary transversality condition. It develops a framework of prestable and stable Morse flow trees, introduces pre-Floer-Gromov and Floer-Gromov convergence, and defines a unique compact topology on the moduli space $\overline{\mathfrak{S}}(L,N)$ by combining edge-convergence with degeneration phenomena such as ghost edges and nodal vertices. The results rely on a Morse-theoretic compactification of edge moduli, a Boardman–Vogt/associahedron structure for the domain trees, and a detailed analysis of gradient flows of local function differences $f_i-f_j$ between sheets of $L$. The construction provides a robust framework for Legendrian contact homology computations in $1$-jet spaces and clarifies degeneration patterns beyond rigid (1-puncture) configurations, with potential implications for multiply-covered configurations and nodal degenerations in the Floer-theoretic setting.
Abstract
We prove a Floer-Gromov compactness type result for (stable) Morse flow trees of Legendrians in 1-jet spaces with simple front singularities satisfying Ekholm's preliminary transversality condition.
