Matching and Independence Complexes Related to Small Grids

Abstract: The topology of the matching complex for the $2\times n$ grid graph is mysterious. We describe a discrete Morse matching for a family of independence complexes $\mathrm{Ind}(\Delta_n<sup>m)$ that include these matching complexes. Using this matching, we determine the dimensions of the chain spaces for the resulting Morse complexes and derive bounds on the location of non-trivial homology groups for certain $\mathrm{Ind}(\Delta_n<sup>m)$. Further, we determine the Euler characteristic of $\mathrm{Ind}(\Delta_n<sup>m)$ and prove that several homology groups of $\mathrm{Ind}(\Delta_n<sup>m)$ are non-zero.