Tootfinder

Legendre-Gauss-Lobatto Collocation Method for Optimal Control via Polynomial Approximations of Differential Equation Vector Fields
Gabriela Abadia-Doyle, William W. Hager, Anil V. Rao
https://arxiv.org/abs/2506.13938

Legendre-Gauss-Lobatto Collocation Method for Optimal Control via Polynomial Approximations of Differential Equation Vector Fields
A new method is described for solving optimal control problems using direct collocation at Legendre-Gauss-Lobatto points. The approach of this paper employs a polynomial approximation of the right-hand side vector field of the differential equations and leads to the following important outcomes. First, the first-order optimality conditions of the LGL integral form are derived, which lead to a full-rank transformed adjoint system and novel costate estimate. Next, a derivative-like form of the LG…

This https://arxiv.org/abs/2308.01456 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_mat…

Decomposing a signed graph into rooted circuits
We prove a precise min-max theorem for the following problem. Let $G$ be an Eulerian graph with a specified set of edges $S \subseteq E(G)$, and let $b$ be a vertex of $G$. Then what is the maximum integer $k$ so that the edge-set of $G$ can be partitioned into $k$ non-zero $b$-trails? That is, each trail must begin and end at $b$ and contain an odd number of edges from~$S$. This theorem is motivated by a connection to vertex-minors and yields two conjectures of Máčajová and Škoviera as cor…

This https://arxiv.org/abs/2401.04391 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_mat…

Kawamata-Miyaoka type inequality for canonical $\mathbb Q$-Fano varieties II: Terminal $\mathbb Q$-Fano threefolds
We prove an optimal Kawamata-Miyaoka type inequality for terminal $\mathbb Q$-Fano threefolds with Fano index at least $3$. As an application, we obtain that any terminal $\mathbb Q$-Fano threefold $X$ satisfies the following Kawamata-Miyaoka type inequality \[ c_1(X)^3 < 3c_2(X)c_1(X). \]

A note concerning the ($S_3$) condition for roots in mixed characteristic
Prashanth Sridhar
https://arxiv.org/abs/2506.09072 https://…

A note concerning the ($S_3$) condition for roots in mixed characteristic
The goal of this note is to record the following curious fact: let $S$ be an unramified regular local ring of mixed characteristic $p>0$. Let $L$ denote the quotient field of $S$ and $K=L(ω)$ with $ω^p\in L$. Let $R$ denote the integral closure of $S$ in $K$. Then $R$ is Cohen-Macaulay if and only if $R$ satisfies Serre's condition $(S_3)$, i.e., the obstruction to the Cohen-Macaulayness of $R$ is in codimension three.

This https://arxiv.org/abs/2408.11643 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_mat…

K3 surfaces with maximal complex multiplication
Following Valloni, we study complex projective K3 surfaces having complex multiplication by rings of integers.

This https://arxiv.org/abs/2401.04391 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_mat…

Kawamata-Miyaoka type inequality for canonical $\mathbb Q$-Fano varieties II: Terminal $\mathbb Q$-Fano threefolds
We prove an optimal Kawamata-Miyaoka type inequality for terminal $\mathbb Q$-Fano threefolds with Fano index at least $3$. As an application, we obtain that any terminal $\mathbb Q$-Fano threefold $X$ satisfies the following Kawamata-Miyaoka type inequality \[ c_1(X)^3 < 3c_2(X)c_1(X). \]

Algebraic identities to prove that a neat finite free algebra is tracically \'etale
Claude Quitt\'e, Henri Lombardi
https://arxiv.org/abs/2506.03851

Algebraic identities to prove that a neat finite free algebra is tracically étale
The central objective of this article is to provide an elementary proof of the following theorem, of which we are unaware of any trace in the existing literature. If $B$ is a net finite free algebra over a commutative ring $A$, then it is tracically étale (its trace form is nondegenerate) and a fortiori étale over A. As indicated in the title, our proof is based on algebraic identities. This confirms the implicit adage that much of the most abstract commutative algebra is concentrated in alge…