Tootfinder

Massiver Cyberangriff auf US-Provider: Erster Einbruch schon ein Jahr früher
2024 ist mutmaßlich chinesischen Angreifern ein massiver Angriff auf US-Provider gelungen. Eine Malware wurde aber offenbar deutlich früher installiert.

This is so out of touch. ICE is ambushing and kidnapping our neighbors and we're going to "cover the entire city with drones"? The SFBOS should reject this "gift"
https://missionlocal.org/2025/06/were-

‘We’re going to be covering the entire city with drones’: Billionaire’s donation to SFPD accepted
San Francisco police commission accepts tech billionaire's gift, to provide cops with drones, cameras and a massive new office

🇺🇦 #NowPlaying on KEXP's #VarietyMix
The Coup:
🎵 Fat Cats, Bigga Fish
#TheCoup
https://chopperman.bandcamp.com/track/the-coup-fat-cats-bigga-fish
https://open.spotify.com/track/74mjiDuK4B0yKtMBoVWt51

game_thrones: Game of Thrones coappearances
Network of coappearances of characters in the Game of Thrones series, by George R. R. Martin, and in particular coappearances in the book "A Storm of Swords." Nodes are unique characters, and edges are weighted by the number of times the two characters' names appeared within 15 words of each other in the text.
This network has 107 nodes and 352 edges.
Tags: Social, Fictional, Weighted

This https://arxiv.org/abs/2412.12633 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_mat…

Arborescences of Random Covering Graphs
A rooted arborescence of a directed graph is a spanning tree directed towards a particular vertex. A recent work of Chepuri et al. showed that the arborescences of a covering graph of a directed graph G are closely related to the arborescences of G. In this paper, we study the weighted sum of arborescences of a random covering graph and give a formula for the expected value, resolving a conjecture of Chepuri et al.

Optimizing Mesh to Improve the Triangular Expansion Algorithm for Computing Visibility Regions
Jan Mikula (Czech Institute of Informatics, Robotics and Cybernetics, Czech Technical University in Prague, Department of Cybernetics, Faculty of Electrical Engineering, Czech Technical University in Prague), Miroslav Kulich (Czech Institute of Informatics, Robotics and Cybernetics, Czech Technical University in Prague)

Optimizing Mesh to Improve the Triangular Expansion Algorithm for Computing Visibility Regions
This paper addresses the problem of improving the query performance of the triangular expansion algorithm (TEA) for computing visibility regions by finding the most advantageous instance of the triangular mesh, the preprocessing structure. The TEA recursively traverses the mesh while keeping track of the visible region, the set of all points visible from a query point in a polygonal world. We show that the measured query time is approximately proportional to the number of triangle edge expansio…

Cohen-Macaulay modules of covariants for cyclic $p$-groups
Jonathan Elmer
https://arxiv.org/abs/2506.03677 https://arxiv.org/pdf/2506…

Cohen-Macaulay modules of covariants for cyclic $p$-groups
Let $G$ be a a finite group, $k$ a field of characteristic dividing $|G|$ and and $V,W$ $kG$-modules. Broer and Chuai showed that if $\mathrm{codim}(V^G) \leq 2$ then the module of covariants $k[V,W]^G = (k[V]\otimes W)^G$ is a Cohen-Macaulay module, hence free over a homogeneous system of parameters for the invariant ring $k[V]^G$. In the present article we prove a general result which allows us to determine whether a set of elements of a free $A$-module is a generating set, for any …

This https://arxiv.org/abs/2506.03947 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_mat…

Block Alpha-Circulant Preconditioners for All-at-Once Diffusion-Based Covariance Operators
Covariance matrices are central to data assimilation and inverse methods derived from statistical estimation theory. Previous work has considered the application of an all-at-once diffusion-based representation of a covariance matrix operator in order to exploit inherent parallellism in the underlying problem. In this paper, we provide practical methods to apply block $α$-circulant preconditioners to the all-at-once system for the case where the main diffusion operation matrix cannot be readil…

@… What are the odds it simply contains a staircase down into a vast, cavernous bunker?

Linear instability of plane Couette and Poiseuille flows
Sergey G. Chefranov, Alexander G. Chefranov
https://arxiv.org/abs/2506.04242 https://

Linear instability of plane Couette and Poiseuille flows
It is shown that linear instability of plane Couette flow can take place even at finite Reynolds numbers which meets with known experimental data. This new result of the linear theory of hydrodynamic stability is obtained only due by abandoning traditional assumption of the longitudinal periodicity of disturbances in the flow direction.