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Chordal graphs are important in the structural and algorithmic graph theory. A digraph analogue of chordal graphs was introduced by Haskin and Rose in 1973 but has not been a subject of active studies until recently when a characterization…

Combinatorics · Mathematics 2021-03-03 Jing Huang , Ying Ying Ye

In this paper we deal with a subclass of chordal graphs, which are simultaneously strictly chordal and interval, the strictly interval graphs. We present a new characterization of the class that leads to a simple linear recognition…

Discrete Mathematics · Computer Science 2026-05-19 Claudia Justel , Lilian Markenzon

Chordal graphs and chordal bigraphs enjoy beautiful characterizations, in terms of forbidden subgraphs, vertex/edge orderings, vertex/edge separating sets, and tree-like representations. In this paper, we introduce chordal signed graphs and…

Combinatorics · Mathematics 2026-01-09 Jing Huang , Ying Ying Ye

Chordal graphs are the graphs in which every cycle of length at least four has a chord. A set $S$ is a vertex separator for vertices $a$ and $b$ if the removal of $S$ of the graph separates $a$ and $b$ into distinct connected components. A…

Discrete Mathematics · Computer Science 2018-03-22 Sérgio H. Nogueira , Vinicius F. dos Santos

Strongly chordal graphs are a subclass of chordal graphs. The interest in this subclass stems from the fact that many problems which are NP-complete for chordal graphs are solvable in polynomial time for this subclass. However, we are not…

Data Structures and Algorithms · Computer Science 2018-04-25 Md. Zamilur Rahman , Asish Mukhopadhyay , Yash P. Aneja

We define strongly chordal digraphs, which generalize strongly chordal graphs and chordal bipartite graphs, and are included in the class of chordal digraphs. They correspond to square 0,1 matrices that admit a simultaneous row and column…

Combinatorics · Mathematics 2019-11-14 Pavol Hell , Cesar Hernandez-Cruz , Jing Huang , Jephian C. -H. Lin

In this work we investigate the chordality of squares and line graph squares of graphs. We prove a sufficient condition for the chordality of squares of graphs not containing induced cycles of length at least five. Moreover, we characterize…

Combinatorics · Mathematics 2017-04-04 Robert Scheidweiler , Sebastian Wiederrecht

Strongly chordal graphs are a subclass of chordal graphs. Farber also established a number of different characterisations for this class of graphs. These include an intersection graph characterisation that is analogous to a similar…

Data Structures and Algorithms · Computer Science 2019-09-06 Md. Zamilur Rahman , Asish Mukhopadhyay

Characterization of k-chordal graphs based on the existence of a "simplicial path" was shown in [Chv{\'a}tal et al. Note: Dirac-type characterizations of graphs without long chordless cycles. Discrete Mathematics, 256, 445-448, 2002]. We…

Combinatorics · Mathematics 2013-01-01 R. Krithika , Rogers Mathew , N. S. Narayanaswamy , N. Sadagopan

We introduce a new subclass of chordal graphs that generalizes split graphs, which we call well-partitioned chordal graphs. Split graphs are graphs that admit a partition of the vertex set into cliques that can be arranged in a star…

Combinatorics · Mathematics 2020-02-26 Jungho Ahn , Lars Jaffke , O-joung Kwon , Paloma T. Lima

A graph is circle if its vertices are in correspondence with a family of chords in a circle in such a way that every two distinct vertices are adjacent if and only if the corresponding chords have nonempty intersection. Even though there…

Discrete Mathematics · Computer Science 2023-04-04 Flavia Bonomo-Braberman , Guillermo A. Durán , Nina Pardal , Martín D. Safe

There is an extensive literature on dynamic algorithms for a large number of graph theoretic problems, particularly for all varieties of shortest path problems. Germane to this paper are a number fully dynamic algorithms that are known for…

Data Structures and Algorithms · Computer Science 2020-02-19 Md. Zamilur Rahman , Asish Mukhopadhyay

In this paper, structural properties of chordal graphs are analysed, in order to establish a relationship between these structures and integer Laplacian eigenvalues. We present the characterization of chordal graphs with equal vertex and…

Discrete Mathematics · Computer Science 2019-07-12 Nair Maria Maia de Abreu , Claudia Marcela Justel , Lilian Markenzon

Distance-regular graphs are a class of regualr graphs with pretty combinatorial symmetry. In 2007, Miklavi\v{c} and Poto\v{c}nik proposed the problem of charaterizing distance-regular Cayley graphs, which can be viewed as a natural…

Combinatorics · Mathematics 2023-11-15 Xueyi Huang , Lu Lu , Xiongfeng Zhan

Strongly chordal digraphs are included in the class of chordal digraphs and generalize strongly chordal graphs and chordal bipartite graphs. They are the digraphs that admit a linear ordering of its vertex set for which their adjacency…

Combinatorics · Mathematics 2025-09-24 Pavol Hell , César Hernández-Cruz , Jing Huang

Comparability graphs are a popular class of graphs. We introduce as the digraph analogue of comparability graphs the class of comparability digraphs. We show that many concepts such as implication classes and the knotting graph for a…

Combinatorics · Mathematics 2022-04-05 Xiao-Lu Gao , Jing Huang , Shou-Jun Xu

A graph is locally chordal if each of its small-radius balls is chordal. In an earlier work [AKK25], the authors and Kobler proved that locally chordal graphs can be characterized by having chordal local covers, by forbidding short cycles…

Combinatorics · Mathematics 2025-12-23 Tara Abrishami , Paul Knappe

mim-width is a recent graph width measure that has seen applications in graph algorithms and problems related to propositional satisfiability. In this paper, we show linear lower bounds for the mim-width of strongly chordal split graphs,…

Discrete Mathematics · Computer Science 2017-01-05 Stefan Mengel

Strictly Chordality-k graphs (SC_k graphs) are graphs which are either cycle free or every induced cycle is exactly k, for some fixed k, k \geq 3. Note that k = 3 and k = 4 are precisely the Chordal graphs and Chordal Bipartite graphs,…

Discrete Mathematics · Computer Science 2017-09-04 S. Dhanalakshmi , N. Sadagopan

A graph $G$ is a {\em chordal-$k$-generalized split graph} if $G$ is chordal and there is a clique $Q$ in $G$ such that every connected component in $G[V \setminus Q]$ has at most $k$ vertices. Thus, chordal-$1$-generalized split graphs are…

Discrete Mathematics · Computer Science 2017-04-28 Andreas Brandstädt , Raffaele Mosca
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