Results 41 to 50 of about 43,687 (165)

Planar 4-critical graphs with four triangles

, 2013
By the Grunbaum-Aksenov Theorem (extending Grotzsch's Theorem) every planar graph with at most three triangles is 3-colorable. However, there are infinitely many planar 4-critical graphs with exactly four triangles. We describe all such graphs.
Borodin, Oleg V., Dvořák, Zdeněk, Kostochka, Alexandr V., Lidický, Bernard, Yancey, Matthew   +4 more
core   +1 more source

Sleep Alters the Velocity of Physiological Brain Pulsations in Humans

Advanced Science, Volume 13, Issue 19, 2 April 2026.
Sleep alters I/CSF oscillatory flow, driven by increased respiratory (29%) and vasomotor pulsation (21%) velocities, while cardiovascular pulsations decreased by (22%). Velocity is quantified using optical flow analysis of MREG data. Spectral power increases alongside these pulsations (spatial correlation, r = 0.35 and r = 0.39, respectively ...
Ahmed Elabasy, Heta Helakari, Tommi Väyrynen, Zalán Rajna, Niko Huotari, Lauri Raitamaa, Ville Isokoski, Matti Järvelä, Mika Kaakinen, Johanna Piispala, Mika Kallio, Vesa Korhonen, Tapio Seppänen, Vesa Kiviniemi   +13 more
wiley   +1 more source

Simplicity of Ore monoid rings

, 2019
Given a non-associative unital ring $R$, a monoid $G$ and a set $\pi$ of additive maps $R \rightarrow R$, we introduce the Ore monoid ring $R[\pi ; G]$, and, in a special case, the differential monoid ring.
Nystedt, Patrik, Richter, Johan, Öinert, Johan   +2 more
core   +1 more source

Ore‐Type Conditions for Existence of a Jellyfish in a Graph

Journal of Graph Theory, Volume 111, Issue 4, Page 124-143, April 2026.
ABSTRACT The famous Dirac's theorem states that for each n ≥ 3 every n‐vertex graph G with minimum degree δ ( G ) ≥ n / 2 has a Hamiltonian cycle. When δ ( G ) < n / 2, this cannot be guaranteed, but the existence of some other specific subgraphs can be provided.
Jaehoon Kim, Alexandr Kostochka, Ruth Luo   +2 more
wiley   +1 more source

Basic Module Theory over Non-Commutative Rings with Computational Aspects of Operator Algebras

, 2013
The present text surveys some relevant situations and results where basic Module Theory interacts with computational aspects of operator algebras. We tried to keep a balance between constructive and algebraic aspects.Comment: To appear in the Proceedings
A. Kandri-Rody, A. Leroy, A. Quadrat, B. Beckermann, B. Strenström, D. Andres, D. Grigoriev, D. Robertz, F. Chyzak, F. Chyzak, F.W. Anderson, G. Bergman, H. Gluesing-Luerssen, J. Apel, J. Apel, J. Gómez-Torrecillas, J. Gómez-Torrecillas, J. Gómez-Torrecillas, J. Gómez-Torrecillas, J.-E. Björk, J.C. McConnell, J.E. Björk, J.L. Bueso, J.L. Bueso, J.L. Bueso, J.L. Bueso, J.L. Bueso, J.L. Bueso, L. Robbiano, M. Barakat, M. Bronstein, M. Giesbrecht, M. Giesbrecht, M. Hazewinkel, M. Hoeij Van, M. Put Van der, M. Saito, M.A. Barkatou, M.F. Singer, N. Jacobson, N. Jacobson, N. Jacobson, O. Lezama, P.J. Hilton, R.C. Churchill, T. Cluzeau, T. Mora, T. Mora, V. Levandovskyy, V. Levandovskyy, V. Levandovskyy, V. Weispfenning, V.P. Gerdt, W. Adams, Ø. Ore   +54 more
core   +1 more source

Supervised Swin Transformer‐Based Predictive Lithological Mapping and Uncertainty Quantification Using Aeromagnetic and Gravity Data

Journal of Geophysical Research: Machine Learning and Computation, Volume 3, Issue 2, April 2026.
Abstract Lithological mapping is essential for the exploration of critical minerals supporting energy transition and national defense. Although recent advancements have incorporated multi‐source data sets and leveraged machine learning and deep learning (DL) methods, lithological mapping continues to face significant challenges, such as data imbalance,
Liang Ding, Gilles Bellefleur, Olivier Boulanger, Phuong Vo   +3 more
wiley   +1 more source

Computing the bound of an Ore polynomial. Applications to factorization

, 2018
We develop a fast algorithm for computing the bound of an Ore polynomial over a skew field, under mild conditions. As an application, we state a criterion for deciding whether a bounded Ore polynomial is irreducible, and we discuss a factorization ...
Gomez-Torrecillas, Jose, Lobillo, F. J., Navarro, Gabriel   +2 more
core   +1 more source

Rethinking Collinearity in Self‐Organizing Maps: Evidence From Geophysical Data Classification

Journal of Geophysical Research: Machine Learning and Computation, Volume 3, Issue 2, April 2026.
Abstract This study examines the impact of collinearity on unsupervised machine learning algorithms (UMLAs), specifically Self‐Organizing Maps (SOMs), for detecting lithological boundaries in geophysical data. Using a multi‐scale experimental framework that includes bivariate isotropic clusters, geologically complex Noddy simulations, and real‐world ...
Limin Xu, Leonardo Feltrin, Eleanor C. R. Green   +2 more
wiley   +1 more source

Nakayama automorphisms of double Ore extensions of Koszul regular algebras

, 2016
Let $A$ be a Koszul Artin-Schelter regular algebra and $\sigma$ an algebra homomorphism from $A$ to $M_{2\times 2}(A)$. We compute the Nakayama automorphisms of a trimmed double Ore extension $A_P[y_1, y_2; \sigma]$ (introduced in \cite{ZZ08}).
Van Oystaeyen, Fred, Zhang, Yinhuo, Zhu, Can   +2 more
core   +1 more source

RETRACTED: Can the chemical industry solve the climate change?On the role of human energy production, renewable energies, and the potential of chemistry as a solution provider

Chemie Ingenieur Technik, Volume 98, Issue 3, Page 98-105, March 2026.
Let us consider an alternative perspective on climate change: The sum of solar radiation and heat generated by human activity result in a net energy input of 1.96 times that of the Sun on the Earth's surface. The expanding global population is expected to exacerbate this issue. Potential solutions are proposed, including replacement and heat recycling.
Martin Bertau, Gerald Steiner
wiley   +1 more source