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U-Nets have been established as a standard architecture for image-to-image learning problems such as segmentation and inverse problems in imaging. For large-scale data, as it for example appears in 3D medical imaging, the U-Net however has…

Machine Learning · Computer Science 2020-07-01 Christian Etmann , Rihuan Ke , Carola-Bibiane Schönlieb

A graph is called bivalent or trivalent if there exists an eigenvector of the graph Laplacian composed from {-1,1} or {-1,0,1}, respectively. These bivalent and trivalent eigenvectors are important for engineering applications, in…

Combinatorics · Mathematics 2025-05-20 Jorge Alencar , Jean-Guy Caputo , Leonardo de Lima , Arnaud Knippel

One of the most basic facts related to the famous Ulam reconstruction conjecture is that the connectedness of a graph can be determined by the deck of its vertex-deleted subgraphs, which are considered up to isomorphism. We strengthen this…

Computational Complexity · Computer Science 2024-06-14 V. Arvind , Johannes Köbler , Oleg Verbitsky

We study two related problems on simple, un-directed graphs: Edge Deletion to Cactus and Spanning Tree to Cactus. Edge Deletion to Cactus has been known to be NP-hard on general graphs at least since 1988. We show improved exact algorithms…

Data Structures and Algorithms · Computer Science 2026-03-31 Sheikh Shakil Akhtar , Geevarghese Philip

Entanglement is a complexity measure of digraphs that origins in fixed-point logics. Its combinatorial purpose is to measure the nested depth of cycles in digraphs. We address the problem of characterizing the structure of graphs of…

Computer Science and Game Theory · Computer Science 2009-04-13 Walid Belkhir

Given a graph $G=(V, E)$, the problem of Graph Burning is to find a sequence of nodes from $V$, called a burning sequence, to burn the whole graph. This is a discrete-step process, and at each step, an unburned vertex is selected as an…

Data Structures and Algorithms · Computer Science 2023-07-18 Rahul Kumar Gautam , Anjeneya Swami Kare , S. Durga Bhavani

This papers considers the problem of maximizing the load that can be served by a power network. We use the commonly accepted Linear DC power network model and consider wo configuration options: switching lines and using FACTS devices. We…

Computational Complexity · Computer Science 2015-07-20 Karsten Lehmann , Alban Grastien , Pascal Van Hentenryck

A graph is $\ell$-reconstructible if it is determined by its multiset of induced subgraphs obtained by deleting $\ell$ vertices. We prove that strongly regular graphs with at least six vertices are $2$-reconstructible.

Combinatorics · Mathematics 2022-10-24 Douglas B. West , Xuding Zhu

We propose a systematic approach to constructing microscopic models with fractional excitations in three-dimensional (3D) space. Building blocks are quantum wires described by the (1+1)-dimensional conformal field theory (CFT) associated…

Strongly Correlated Electrons · Physics 2019-06-19 Yohei Fuji , Akira Furusaki

We consider network graphs $G=(V,E)$ in which adjacent nodes share common secrets. In this setting, certain techniques for perfect end-to-end security (in the sense of confidentiality, authenticity (implying integrity) and availability,…

Cryptography and Security · Computer Science 2023-01-19 Stefan Rass

The 5x5, 6rt(3)x6rt(3)-R30deg, and graphene-covered 6rt(3)x6rt(3)-R30deg reconstructions of the SiC(0001) surface are studied by scanning tunneling microscopy and spectroscopy. For the 5x5 structure a rich spectrum of surface states is…

Materials Science · Physics 2010-11-23 Shu Nie , R. M. Feenstra

We determine a lower bound for the number of edges of a 2-connected maximal nontraceable graph, and present a construction of an infinite family of maximal nontraceable graphs that realize this bound.

Combinatorics · Mathematics 2007-05-23 Marietjie Frick , Joy Singleton

We present a novel characterization of complex networks, based on the potential of an associated Schr\"odinger equation. The potential is designed so that the energy spectrum of the Schr\"odinger equation coincides with the graph spectrum…

Higher-order interactions provide a nuanced understanding of the relational structure of complex systems beyond traditional pairwise interactions. However, higher-order network analyses also incur more cumbersome interpretations and greater…

Physics and Society · Physics 2026-01-07 Alec Kirkley , Helcio Felippe , Federico Battiston

We show that the problem of recovering the topology and admittance of an electrical network from power and voltage data at all vertices is often ill-posed, and sometimes it even has multiple solutions. We reformulate the problem to seek for…

Optimization and Control · Mathematics 2026-01-19 Álvaro Samperio

The large size of multiscale, distribution and transmission, power grids hinder fast system-wide estimation and real-time control and optimization of operations. This paper studies graph reduction methods of power grids that are favorable…

Systems and Control · Computer Science 2018-10-05 Colin Grudzien , Deepjyoti Deka , Michael Chertkov , Scott N Backhaus

A constructive characterization of the class of uniformly $4$-connected graphs is presented. The characterization is based on the application of graph operations to appropriate vertex and edge sets in uniformly $4$-connected graphs, that…

Combinatorics · Mathematics 2025-07-11 Xiang Chen , Shuai Kou , Chengfu Qin , Liqiong Xu , Weihua Yang

This article presents a theoretical investigation of generalized encoded forms of networks in a uniform multidimensional space. First, we study encoded networks with (finite) arbitrary node dimensions (or aspects), such as time instants or…

Discrete Mathematics · Computer Science 2023-04-25 Felipe S. Abrahão , Klaus Wehmuth , Hector Zenil , Artur Ziviani

Several methods have recently been developed for joint structure learning of multiple (related) graphical models or networks. These methods treat individual networks as exchangeable, such that each pair of networks are equally encouraged to…

Methodology · Statistics 2014-06-03 Chris J. Oates , Sach Mukherjee

Using an iterative tree construction we show that for simple computable subsets of the Cantor space Hausdorff, constructive and computable dimensions might be incomputable.

Logic in Computer Science · Computer Science 2024-05-24 Ludwig Staiger