Title: Linear Structural Equation Models

Abstract: Linear structural equation models (L-SEMs) are a class of multivariate statistical models which study possible causal dependencies among variables. These models are associated with a path diagram, a graph with a directed acyclic part and a bidirected part. When a model has been specified, it is of interest to determine whether the model parameters can be recovered from the covariance matrix which they define. In this talk we will introduce the topic of causal inference using L-SEMs and present recent progress on generic identifiability using algebraic methods.

Abstract: Khovanskii bases (introuduced by Kiumars Kaveh and Christopher Manon) are an important tool used to study $\mathbb{K}$-domains relative to a valuation, and in fact, are a vast generalization of the notion of a SAGBI basis. We begin by introducing Khovanskii bases and provide several examples. We are particularly interested in the case when a pair $(A, \mathfrak{v})$ has a finite Khovanskii basis. Next, we discuss $T$-varieties which are a natural generalization of toric varieties. We will see how affine $T$-varieties arise out of the quasi-combinatorial data of a polyhedral divisor via the construction of J"urgen Hausen and Klaus Altmann. Finally, we will see a result by Nathan Ilten and C. Manon: for any homogeneous valuation $\mathfrak{v}$ on the coordinate ring of a rational complexity $1$ $T$-variety, there is an embedding whose coordinates are a Khovanskii basis for $\mathfrak{v}$.   

Abstract: Khovanskii bases (introuduced by Kiumars Kaveh and Christopher Manon) are an important tool used to study $\mathbb{K}$-domains relative to a valuation, and in fact, are a vast generalization of the notion of a SAGBI basis. We begin by introducing Khovanskii bases and provide several examples. We are particularly interested in the case when a pair $(A, \mathfrak{v})$ has a finite Khovanskii basis. Next, we discuss $T$-varieties which are a natural generalization of toric varieties. We will see how affine $T$-varieties arise out of the quasi-combinatorial data of a polyhedral divisor via the construction of J"urgen Hausen and Klaus Altmann. Finally, we will see a result by Nathan Ilten and C. Manon: for any homogeneous valuation $\mathfrak{v}$ on the coordinate ring of a rational complexity $1$ $T$-variety, there is an embedding whose coordinates are a Khovanskii basis for $\mathfrak{v}$.   

Title: Asymptotic Algebra and FI-modules

Abstract: Symmetric ideals in increasingly larger polynomial rings that form an ascending chain arise in various contexts like algebraic statistics, commutative algebra, and representation theory. In this talk we discuss some recent results and open questions on the asymptotic behavior of algebraic/homological invariants of ideals in such chains. Our approach is based on FI-modules with varying coefficients and various related techniques. This talk is based on joint work with Dinh Van Le, Uwe Nagel, and Hop D. Nguyen.

Title: Motivic manifestations of matroids

Abstract: A matroid is a combinatorial object which abstracts the notion of (linear or algebraic) "independence. Recent work of Adiprasito-Huh-Katz demonstrates a surprising connection to algebraic geometry: every matroid possesses a cohomology ring'' which behaves like the Chow ring of a smooth projective variety. In this talk, I will define another "algebro-geometric'' matroid invariant, the motivic zeta function of a matroid. I will assume no prior knowledge of matroids or motivic zeta functions. This is work in progress with Jeremy Usatine.

Title: Balanced shellings on manifolds

Abstract: A classical result by Pachner states that any two PL homoeomorphic manifolds with boundary are related by a sequence of shellings and inverse shellings. We show that, for balanced manifolds, such a sequence can be chosen in such a way that in each step balancedness is preserved. This is joint work with Lorenzo Venturello.