Jack H. Koolen

According to our database1, Jack H. Koolen authored at least 117 papers between 1990 and 2021.

Collaborative distances:
  • Dijkstra number2 of four.
  • Erdős number3 of two.

Timeline

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Bibliography

2021
Connectivity concerning the last two subconstituents of a <i>Q</i>-polynomial distance-regular graph.
J. Comb. Theory, Ser. A, 2021

2020
On the Cheeger constant for distance-regular graphs.
J. Comb. Theory, Ser. A, 2020

On the nonexistence of pseudo-generalized quadrangles.
Eur. J. Comb., 2020

A spectral characterization of the <i>s</i>-clique extension of the triangular graphs.
Discuss. Math. Graph Theory, 2020

On the spectrum and linear programming bound for hypergraphs.
CoRR, 2020

2019
A new characterization of the dual polar graphs.
J. Comb. Theory, Ser. B, 2019

A generalization of a theorem of Hoffman.
J. Comb. Theory, Ser. B, 2019

On the Integrability of Strongly Regular Graphs.
Graphs Comb., 2019

There Does Not Exist a Distance-Regular Graph with Intersection Array {80, 54, 12; 1, 6, 60}.
Graphs Comb., 2019

On 2-walk-regular graphs with a large intersection number c2.
Eur. J. Comb., 2019

A spectral characterization of the s-clique extension of the square grid graphs.
Eur. J. Comb., 2019

Distance-regular graphs without 4-claws.
Eur. J. Comb., 2019

The polytopal structure of the tight-span of a totally split-decomposable metric.
Discret. Math., 2019

Another construction of edge-regular graphs with regular cliques.
Discret. Math., 2019

Non-Bipartite Distance-Regular Graphs with a Small Smallest Eigenvalue.
Electron. J. Comb., 2019

A Characterization of the Graphs of Bilinear (d×d)-Forms over F<sub>2</sub>.
Comb., 2019

2018
A valency bound for distance-regular graphs.
J. Comb. Theory, Ser. A, 2018

Partially metric association schemes with a multiplicity three.
J. Comb. Theory, Ser. B, 2018

Graphs with three eigenvalues and second largest eigenvalue at most 1.
J. Comb. Theory, Ser. B, 2018

Edge-regular graphs with regular cliques.
Eur. J. Comb., 2018

Addressing Johnson graphs, complete multipartite graphs, odd cycles and other graphs.
CoRR, 2018

A spectral version of the Moore problem for bipartite regular graphs.
CoRR, 2018

Open problems in the spectral theory of signed graphs.
Art Discret. Appl. Math., 2018

2017
Max-cut and extendability of matchings in distance-regular graphs.
Eur. J. Comb., 2017

Light tails and the Hermitian dual polar graphs.
Des. Codes Cryptogr., 2017

A generalization of a theorem of Neumaier.
Des. Codes Cryptogr., 2017

Preface to the special issue dedicated to Andries E. Brouwer.
Des. Codes Cryptogr., 2017

An Application of Hoffman Graphs for Spectral Characterizations of Graphs.
Electron. J. Comb., 2017

2016
Maximizing the Order of a Regular Graph of Given Valency and Second Eigenvalue.
SIAM J. Discret. Math., 2016

Equiangular lines in Euclidean spaces.
J. Comb. Theory, Ser. A, 2016

Biregular graphs with three eigenvalues.
Eur. J. Comb., 2016

Arithmetic completely regular codes.
Discret. Math. Theor. Comput. Sci., 2016

A collection of results concerning electric resistance and simple random walk on distance-regular graphs.
Discret. Math., 2016

2-Walk-Regular Dihedrants from Group-Divisible Designs.
Electron. J. Comb., 2016

Characterizing block graphs in terms of their vertex-induced partitions.
Australas. J Comb., 2016

2015
Edge-signed graphs with smallest eigenvalue greater than -2.
J. Comb. Theory, Ser. B, 2015

Some Results on the Eigenvalues of Distance-Regular Graphs.
Graphs Comb., 2015

Optimal realizations of two-dimensional, totally-decomposable metrics.
Discret. Math., 2015

Large regular graphs with given valency and second eigenvalue.
CoRR, 2015

2014
Regular graphs with maximal energy per vertex.
J. Comb. Theory, Ser. B, 2014

Disconnecting strongly regular graphs.
Eur. J. Comb., 2014

On geometric distance-regular graphs with diameter three.
Eur. J. Comb., 2014

On fat Hoffman graphs with smallest eigenvalue at least -3.
Ars Math. Contemp., 2014

2013
There are only finitely many distance-regular graphs with valency k at least three, fixed ratio k<sub>2</sub>/k and large diameter.
J. Comb. Theory, Ser. B, 2013

A note on distance-regular graphs with a small number of vertices compared to the valency.
Eur. J. Comb., 2013

On electric resistances for distance-regular graphs.
Eur. J. Comb., 2013

Distance-Regular Graphs with a Relatively Small Eigenvalue Multiplicity.
Electron. J. Comb., 2013

2012
Distance-regular graphs with a<sub>2</sub> or c<sub>2</sub> at least half the valency.
J. Comb. Theory, Ser. A, 2012

On a conjecture of Brouwer involving the connectivity of strongly regular graphs.
J. Comb. Theory, Ser. A, 2012

Injective optimal realizations of finite metric spaces.
Discret. Math., 2012

A relationship between the diameter and the intersection number c 2 for a distance-regular graph.
Des. Codes Cryptogr., 2012

Basic Phylogenetic Combinatorics.
Cambridge University Press, ISBN: 978-0-521-76832-0, 2012

2011
Blocks and Cut Vertices of the Buneman Graph.
SIAM J. Discret. Math., 2011

Classification of the family AT4(qs, q, q) of antipodal tight graphs.
J. Comb. Theory, Ser. A, 2011

On a conjecture of Brouwer regarding the connectivity of strongly regular graphs
CoRR, 2011

2010
On distance-regular graphs with smallest eigenvalue at least -m.
J. Comb. Theory, Ser. B, 2010

Delsarte Set Graphs with Small <i>c</i><sub>2</sub>.
Graphs Comb., 2010

Shilla distance-regular graphs.
Eur. J. Comb., 2010

A lower bound for the spectral radius of graphs with fixed diameter.
Eur. J. Comb., 2010

A Conjecture of Biggs Concerning the Resistance of a Distance-Regular Graph.
Electron. J. Comb., 2010

On Sum of Powers of the Laplacian and Signless Laplacian Eigenvalues of Graphs.
Electron. J. Comb., 2010

An Algorithm for Computing Cutpoints in Finite Metric Spaces.
J. Classif., 2010

2009
Optimal realizations of generic five-point metrics.
Eur. J. Comb., 2009

The vertex-connectivity of a distance-regular graph.
Eur. J. Comb., 2009

The spectra of the local graphs of the twisted Grassmann graphs.
Eur. J. Comb., 2009

Arithmetic completely regular codes
CoRR, 2009

Bounds for the Hückel Energy of a Graph.
Electron. J. Comb., 2009

Quartets in maximal weakly compatible split systems.
Appl. Math. Lett., 2009

A graph-theoretical invariant of topological spaces.
Appl. Math. Lett., 2009

2008
Triangle-free distance-regular graphs with an eigenvalue multiplicity equal to their valency and diameter 3.
Eur. J. Comb., 2008

Compatible decompositions and block realizations of finite metrics.
Eur. J. Comb., 2008

On triangle-free distance-regular graphs with an eigenvalue multiplicity equal to the valency.
Eur. J. Comb., 2008

Counting vertices and cubes in median graphs of circular split systems.
Eur. J. Comb., 2008

Preface.
Discret. Math., 2008

Characterizing Cell-Decomposable Metrics.
Electron. J. Comb., 2008

Block realizations of finite metrics and the tight-span construction I: The embedding theorem.
Appl. Math. Lett., 2008

Cut points in metric spaces.
Appl. Math. Lett., 2008

2007
Two theorems concerning the Bannai-Ito conjecture.
Eur. J. Comb., 2007

Delsarte clique graphs.
Eur. J. Comb., 2007

Concerning the Relationship between Realizations and Tight Spans of Finite Metrics.
Discret. Comput. Geom., 2007

An Algorithm for Computing Virtual Cut Points in Finite Metric Spaces.
Proceedings of the Combinatorial Optimization and Applications, 2007

2006
Characterizing distance-regularity of graphs by the spectrum.
J. Comb. Theory, Ser. A, 2006

On the structure of the tight-span of a totally split-decomposable metric.
Eur. J. Comb., 2006

Improving diameter bounds for distance-regular graphs.
Eur. J. Comb., 2006

Combinatorics of lopsided sets.
Eur. J. Comb., 2006

2005
Triangle- and pentagon-free distance-regular graphs with an eigenvalue multiplicity equal to the valency.
J. Comb. Theory, Ser. B, 2005

A generalization of an inequality of Brouwer-Wilbrink.
J. Comb. Theory, Ser. A, 2005

The tight span of an antipodal metric space - Part I: : Combinatorial properties.
Discret. Math., 2005

Some Interlacing Results for the Eigenvalues of Distance-regular graphs.
Des. Codes Cryptogr., 2005

Delta additive and Delta ultra-additive maps, Gromov's trees, and the Farris transform.
Discret. Appl. Math., 2005

2004
A Note on Regular Near Polygons.
Graphs Comb., 2004

The structure of spherical graphs.
Eur. J. Comb., 2004

The Tight Span of an Antipodal Metric Space: Part II--Geometrical Properties.
Discret. Comput. Geom., 2004

2003
Width and dual width of subsets in polynomial association schemes.
J. Comb. Theory, Ser. A, 2003

Maximal Energy Bipartite Graphs.
Graphs Comb., 2003

Addendum to "on line arrangements in the hyperbolic plane" [European J. Combin.23 (2002) 549-557].
Eur. J. Comb., 2003

A bound for the number of columns l<sub>(c, a, b)</sub> in the intersection array of a distance-regular graph.
Eur. J. Comb., 2003

A Root Graph that is Locally the Line Graph of the Peterson Graph.
Discret. Math., 2003

2002
On a Conjecture of Bannai and Ito: There are Finitely Many Distance-regular Graphs with Degree 5, 6 or 7.
Eur. J. Comb., 2002

Hyperbolic Bridged Graphs.
Eur. J. Comb., 2002

On Line Arrangements in the Hyperbolic Plane.
Eur. J. Comb., 2002

Krein parameters and antipodal tight graphs with diameter 3 and 4.
Discret. Math., 2002

2001
Six Points Suffice: How to Check for Metric Consistency.
Eur. J. Comb., 2001

Maximal Energy Graphs.
Adv. Appl. Math., 2001

2000
A Classification of the Six-point Prime Metrics.
Eur. J. Comb., 2000

Nonexistence of some Antipodal Distance-regular Graphs of Diameter Four.
Eur. J. Comb., 2000

Equilateral Dimension of the Rectilinear Space.
Des. Codes Cryptogr., 2000

A Local Approach to 1-Homogeneous Graphs.
Des. Codes Cryptogr., 2000

1999
Graphs which Locally Mirror the Hypercube Structure.
Inf. Process. Lett., 1999

1998
The coherency index.
Discret. Math., 1998

The Distance-regular Graphs with Intersection Number a<sub>1</sub>!=0 and with an Eigenvalue -1-(b<sub>1</sub>/2).
Comb., 1998

1995
A Characterization of the Doob Graphs.
J. Comb. Theory, Ser. B, 1995

1994
Distance-regular Graphs the Distance Matrix of which has Only One Positive Eigenvalue.
Eur. J. Comb., 1994

1993
On uniformly geodetic graphs.
Graphs Comb., 1993

A new infinite series of regular uniformly geodetic code graphs.
Discret. Math., 1993

1992
A new condition for distance-regular graphs.
Eur. J. Comb., 1992

1990
Perfect modes with distinct protective radii.
Discret. Math., 1990


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