Minimally non-Golod face rings and Massey products

Massey products and the Golod property for simplicially resolvable rings

We apply algebraic Morse theory to the Taylor resolution of a monomial ring $R = S/I$ to obtain an $A_{\infty}$-structure on the minimal free resolution of $R$. Using this structure we describe the vanishing of higher Massey products in case the minimal free resolution is simplicial. Under this assumption, we show that R is Golod if and only if the product on $\text{Tor}^S(R, k)$ vanishes. Lastly, we give two combinatorial characterizations of the Golod property in this case.

Connected sums of sphere products and minimally non-Golod complexes

We show that if the moment-angle complex $\mathcal{Z}_K$ associated to a simplicial complex $K$ is homotopy equivalent to a connected sum of sphere products with two spheres in each product, then $K$ decomposes as the simplicial join of an $n$-simplex $Δ^n$ and a minimally non-Golod complex. In particular, we prove that $K$ is minimally non-Golod for every moment-angle complex $\mathcal{Z}_K$ homeomorphic to a connected sum of two-fold products of spheres, answering a question of Grbić, Panov, Theriault and Wu.

A non-Golod ring with a trivial product on its Koszul homology

We present a monomial ideal $\mathfrak{a} \subset S$ such that $S/\mathfrak{a}$ is not Golod, even though the product on its Koszul homology is trivial. This constitutes a counterexample to a well-known result by Berglund and Jöllenbeck (the error can be traced to a mistake in an earlier article by Jöllenbeck). On the positive side, we show that if $R$ is a monomial ring such that the $r$-ary Massey product vanish for all $r \leq \max(2, \mathrm{reg} R-2)$, then $R$ is Golod. In particular, if $R$ is the Stanley-Reisner ring of a simplicial complex of dimension at most $3$, then $R$ is Golod i…

Families of minimally non-Golod complexes and their polyhedral products

We consider families of simple polytopes $P$ and simplicial complexes $K$ well-known in polytope theory and convex geometry, and show that their moment-angle complexes have some remarkable homotopy properties which depend on combinatorics of the underlying complexes and algebraic properties of their Stanley--Reisner rings. We introduce infinite series of Golod and minimally non-Golod simplicial complexes $K$ with moment-angle complexes $\mathcal Z_K$ having free integral cohomology but not homotopy equivalent to a wedge of spheres or a connected sum of products of spheres respectively. We then…

单纯球面与立方球面、多面体乘积及 Nevo-Petersen 猜想

Simplicial vs. cubical spheres, polyhedral products and the Nevo-Petersen conjecture

本文通过多面体乘积与神经复形方法分类 flag Murai 球面和极小非 Golod Bier 球面，证明前者满足 Nevo-Petersen 猜想，并引入立方 Bier 球面研究其组合与几何性质。