Results 51 to 60 of about 11,002 (236)
EMS Surveys in Mathematical Sciences, 2021 Torelli groups are subgroups of mapping class groups that consist of those diffeomorphism classes that act trivially on the homology of the associated closed surface. The Johnson homomorphism, defined by Dennis Johnson, and its generalization, defined by S. Morita, are tools for understanding Torelli groups.
openaire +3 more sources
Line Graphs of Multigraphs and the Forbidden Graph E 6
Journal of Graph Theory, EarlyView.ABSTRACT The line graph Γ of a multigraph Δ is the graph whose vertices are the edges of Δ, where two such edges are adjacent if and only if they meet in a single vertex of Δ. We provide several characterizations of such line graphs and in particular show that a graph is a line graph if and only if it does not contain one of the 32 graphs, all of which
Hans Cuypers
wiley +1 more source
On the stability of -homomorphisms [PDF]
Nonlinear Analysis: Theory, Methods & Applications, 2005 8 pages, minor ...
Baak, Choonkil, Moslehian, Mohammad Sal
openaire +3 more sources
Continuous MDP Homomorphisms and Homomorphic Policy Gradient
Advances in Neural Information Processing Systems 35, 2022 Abstraction has been widely studied as a way to improve the efficiency and generalization of reinforcement learning algorithms. In this paper, we study abstraction in the continuous-control setting. We extend the definition of MDP homomorphisms to encompass continuous actions in continuous state spaces.
Sahand Rezaei-Shoshtari +4 more
openaire +4 more sources
On Sparsity Conditions Guaranteeing a Fractional Coloring
Journal of Graph Theory, EarlyView.ABSTRACT A graph has an ( a : b ) $(a:b)$ ‐coloring if there exists an assignment from the vertices to subsets of { 1 , … , a } $\{1,\ldots ,a\}$ with size b $b$ such that adjacent vertices are assigned disjoint subsets. Odd girth at least 2 k + 1 $2k+1$ is a necessary condition for a graph to have a ( 2 k + 1 : k ) $(2k+1:k)$‐coloring.
Ilkyoo Choi
wiley +1 more source
Homomorphisms of the lattice of slowly oscillating functions on the half-line
Applied General TopologyWe study the space H(SO) of all homomorphisms of the vector lattice of all slowly oscillating functions on the half-line ℍ = [ 0 , ∞ ) . In contrast to the case of homomorphisms of uniformly continuous functions, it is shown that a homomorphism in H(SO ...
Yutaka Iwamoto
doaj +1 more source
Homomorphic Preimages of Geometric Paths
Discussiones Mathematicae Graph Theory, 2018 A graph G is a homomorphic preimage of another graph H, or equivalently G is H-colorable, if there exists a graph homomorphism f : G → H. A geometric graph Ḡ is a simple graph G together with a straight line drawing of G in the plane with the vertices in
Cockburn Sally
doaj +1 more source
Factoring Continuous Homomorphisms Defined on Submonoids of Products of Topologized Monoids
Axioms, 2019 We study factorization properties of continuous homomorphisms defined on submonoids of products of topologized monoids. We prove that if S is an ω-retractable submonoid of a product D = ∏ i ∈ I D i of topologized monoids ...
Mikhail Tkachenko
doaj +1 more source
Saturated Partial Embeddings of Planar Graphs
Journal of Graph Theory, EarlyView.ABSTRACT In this work, we study how far one can deviate from optimal behavior when embedding a planar graph. For a planar graph G $G$, we say that a plane subgraph H ⊆ G $H\subseteq G$ is a plane‐saturated subgraph if adding any edge (possibly with new vertices) to H $H$ would either violate planarity or make the resulting graph no longer a subgraph of
Alexander Clifton, Nika Salia
wiley +1 more source