Results 201 to 210 of about 9,360 (297)

Orientations of Graphs With at Most One Directed Path Between Every Pair of Vertices

open access: yesJournal of Graph Theory, EarlyView.
ABSTRACT Given a graph G $G$, we say that an orientation D $D$ of G $G$ is a KT orientation if, for all u , v ∈ V ( D ) $u,v\in V(D)$, there is at most one directed path (in any direction) between u $u$ and v $v$. Graphs that admit such orientations have been used to construct graphs with large chromatic number and small clique number that served as ...
Barbora Dohnalová   +3 more
wiley   +1 more source

On the Hardness of Switching to a Small Number of Edges

open access: yesJournal of Graph Theory, EarlyView.
ABSTRACT Seidel's switching is a graph operation which makes a given vertex adjacent to precisely those vertices to which it was non‐adjacent before, while keeping the rest of the graph unchanged. Two graphs are called switching‐equivalent if one can be made isomorphic to the other one by a sequence of switches. Jelínková et al. [DMTCS 13, no. 2, 2011]
Vít Jelínek   +2 more
wiley   +1 more source

Stable Cuts, NAC‐Colourings and Flexible Realisations of Graphs

open access: yesJournal of Graph Theory, EarlyView.
ABSTRACT A (2‐dimensional) realisation of a graph G $G$ is a pair ( G , p ) $(G,p)$, where p $p$ maps the vertices of G $G$ to R 2 ${{\mathbb{R}}}^{2}$. A realisation is flexible if it can be continuously deformed while keeping the edge lengths fixed, and rigid otherwise.
Katie Clinch   +5 more
wiley   +1 more source

A Min–Max Relation on Dicuts and Dijoins in Weighted Chordal Digraphs

open access: yesJournal of Graph Theory, EarlyView.
ABSTRACT In a digraph, a dicut is a cut where all the arcs cross in one direction. A dijoin is a subset of arcs that intersects every dicut. Edmonds and Giles conjectured that in a weighted digraph, the minimum weight of a dicut is equal to the maximum size of a packing of dijoins. This has been disproved. However, the unweighted version conjectured by
Gérard Cornuéjols, Siyue Liu, R. Ravi
wiley   +1 more source

On Fork‐Free t‐Perfect Graphs

open access: yesJournal of Graph Theory, EarlyView.
ABSTRACT In an effort to understand the complexity of the maximum independent set problem, Chvátal introduced t‐perfect graphs. While a full characterization of this class remains open, important progress has been made for claw‐free graphs [Bruhn and Stein, Math. Program. 2012] and P 5 ${P}_{5}$‐free graphs [Bruhn and Fuchs, SIAM J. Discrete Math. 2017]
Yixin Cao, Shenghua Wang
wiley   +1 more source

b -Hurwitz numbers from refined topological recursion. [PDF]

open access: yesMath Ann
Kumar Chidambaram N   +2 more
europepmc   +1 more source

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