Jack H. Koolen

115 papers Journal 115
YearRankTypeTitle / Venue / Authors
2026 J jnl
A Bose-Laskar-Hoffman theory for μ -bounded graphs with fixed smallest eigenvalue.
Eur. J. Comb.
Jack H. Koolen, Hong-Jun Ge, Chenhui Lv, Qianqian Yang
2026 J jnl
A characterization of the Grassmann graphs: One missing case.
Eur. J. Comb.
Jack H. Koolen, Chenhui Lv, Alexander L. Gavrilyuk
2026 J jnl
Bounding the parameter β of a distance-regular graph with classical parameters.
J. Comb. Theory, Ser. A
Chenhui Lv, Jack H. Koolen
2026 J jnl
Geometry of ample/lopsided sets.
CoRR
Hans-Jürgen Bandelt, Victor Chepoi, Andreas W. M. Dress, Jack H. Koolen
2025 J jnl
A characterization of the Grassmann graphs.
J. Comb. Theory B
Alexander L. Gavrilyuk, Jack H. Koolen
2025 J jnl
Bounding the intersection number c2 of a distance-regular graph with classical parameters (D,b,α,β) in terms of b.
Discret. Math.
Jack H. Koolen, Chenhui Lv, Jongyook Park, Qianqian Yang
2025 J jnl
Characterizations of amorphic schemes and fusions of pairs.
J. Comb. Theory, Ser. A
Edwin R. van Dam, Jack H. Koolen, Yanzhen Xiong
2025 J jnl
Edge-regular graphs with fixed smallest eigenvalue with an application to Neumaier graphs.
Discret. Math.
Qianqian Yang, Jack H. Koolen
2025 J jnl
Non-existence of two infinite families of strongly regular graphs.
Eur. J. Comb.
Jack H. Koolen, Brhane Gebremichel, Jeong Rye Park, Jongyook Park
2025 J jnl
Non-geometric distance-regular graphs of diameter at least 3 with smallest eigenvalue at least -3.
Eur. J. Comb.
Jack H. Koolen, Kefan Yu, Xiaoye Liang, Harrison Choi, Greg Markowsky
2025 J jnl
On Co-Edge-Regular Graphs with $4$ Distinct Eigenvalues.
Electron. J. Comb.
Hong-Jun Ge, Jack H. Koolen
2024 J jnl
Distance-regular graphs with a few q-distance eigenvalues.
Discret. Math.
Mamoon Abdullah, Brhane Gebremichel, Sakander Hayat, Jack H. Koolen
2024 J jnl
On the (Non-)Existence of Tight Distance-Regular Graphs: a Local Approach.
Electron. J. Comb.
Jack H. Koolen, Jae-Ho Lee, Shuang-Dong Li, Yun-Han Li, Xiaoye Liang, Ying-Ying Tan
2023 J jnl
A New Feasibility Condition for the AT4 Family.
Electron. J. Comb.
Zheng-Jiang Xia, Jae-Ho Lee, Jack H. Koolen
2023 J jnl
An infinite class of Neumaier graphs and non-existence results.
J. Comb. Theory A
Aida Abiad, Wouter Castryck, Maarten De Boeck, Jack H. Koolen, Sjanne Zeijlemaker
2023 J jnl
Correction to: Thin Q-Polynomial Distance-Regular Graphs Have Bounded c
Graphs Comb.
Ying-Ying Tan, Jack H. Koolen, Mengyue Cao, Jongyook Park
2022 J jnl
Neumaier graphs with few eigenvalues.
Des. Codes Cryptogr.
Aida Abiad, Bart De Bruyn, Jozefien D'haeseleer, Jack H. Koolen
2022 J jnl
On the spectrum and linear programming bound for hypergraphs.
Eur. J. Comb.
Sebastian M. Cioaba, Jack H. Koolen, Masato Mimura, Hiroshi Nozaki, Takayuki Okuda
2022 J jnl
Remarks on pseudo-vertex-transitive graphs with small diameter.
Discret. Math.
Jack H. Koolen, Jae-Ho Lee, Ying-Ying Tan
2022 J jnl
The 2-partially distance-regular graphs such that their second largest local eigenvalues are at most one.
Discret. Math.
Yuanjiang Zhang, Xiaoye Liang, Jack H. Koolen
2022 J jnl
The Lemmens-Seidel conjecture and forbidden subgraphs.
J. Comb. Theory A
Mengyue Cao, Jack H. Koolen, Yen-Chi Roger Lin, Wei-Hsuan Yu
2022 J jnl
There Does Not Exist a Strongly Regular Graph with Parameters $(1911, 270, 105, 27)$.
Electron. J. Comb.
Jack H. Koolen, Brhane Gebremichel
2022 J jnl
Thin Q-Polynomial Distance-Regular Graphs Have Bounded c
Graphs Comb.
Ying-Ying Tan, Jack H. Koolen, Mengyue Cao, Jongyook Park
2021 J jnl
Addressing Johnson Graphs, Complete Multipartite Graphs, Odd Cycles, and Random Graphs.
Exp. Math.
Noga Alon, Sebastian M. Cioaba, Brandon D. Gilbert, Jack H. Koolen, Brendan D. McKay
2021 J jnl
Augmenting the Delsarte bound: A forbidden interval for the order of maximal cliques in strongly regular graphs.
Eur. J. Comb.
Gary R. W. Greaves, Jack H. Koolen, Jongyook Park
2021 J jnl
Connectivity concerning the last two subconstituents of a
J. Comb. Theory A
Sebastian M. Cioaba, Jack H. Koolen, Paul M. Terwilliger
2021 J jnl
Maximality of Seidel matrices and switching roots of graphs.
Graphs Comb.
Mengyue Cao, Jack H. Koolen, Akihiro Munemasa, Kiyoto Yoshino
2021 J jnl
Preface to the special issue dedicated to Professors Eiichi Bannai and Hikoe Enomoto on their 75th birthdays.
Graphs Comb.
Jack H. Koolen, Akihiro Munemasa, Atsuhiro Nakamoto, Katsuhiro Ota, Akira Saito
2021 J jnl
Recent Progress on Graphs with Fixed Smallest Adjacency Eigenvalue: A Survey.
Graphs Comb.
Jack H. Koolen, Mengyue Cao, Qianqian Yang
2021 J jnl
Thin Distance-Regular Graphs with Classical Parameters $(D, q, q, \frac{q^{t}-1}{q-1}-1)$ with $t> D$ are the Grassmann Graphs.
Electron. J. Comb.
Ying-Ying Tan, Xiaoye Liang, Jack H. Koolen
2021 J jnl
Two characterizations of the grid graphs.
Discret. Math.
Brhane Gebremichel, Mengyue Cao, Jack H. Koolen
2020 J jnl
A spectral characterization of the
Discuss. Math. Graph Theory
Jack H. Koolen, Ying-Ying Tan, Zheng-Jiang Xia
2020 J jnl
On the Cheeger constant for distance-regular graphs.
J. Comb. Theory A
Zhi Qiao, Jack H. Koolen, Greg Markowsky
2020 J jnl
On the nonexistence of pseudo-generalized quadrangles.
Eur. J. Comb.
Ivan Guo, Jack H. Koolen, Greg Markowsky, Jongyook Park
2020 J jnl
On the spectrum and linear programming bound for hypergraphs.
CoRR
Sebastian M. Cioaba, Jack H. Koolen, Masato Mimura, Hiroshi Nozaki, Takayuki Okuda
2019 J jnl
A Characterization of the Graphs of Bilinear (d×d)-Forms over F
Comb.
Alexander L. Gavrilyuk, Jack H. Koolen
2019 J jnl
A generalization of a theorem of Hoffman.
J. Comb. Theory B
Jack H. Koolen, Qianqian Yang, Jae Young Yang
2019 J jnl
A spectral characterization of the s-clique extension of the square grid graphs.
Eur. J. Comb.
Sakander Hayat, Jack H. Koolen, Muhammad Riaz
2019 J jnl
Another construction of edge-regular graphs with regular cliques.
Discret. Math.
Gary R. W. Greaves, Jack H. Koolen
2019 J jnl
Distance-regular graphs without 4-claws.
Eur. J. Comb.
Sejeong Bang, Alexander L. Gavrilyuk, Jack H. Koolen
2019 J jnl
Non-Bipartite Distance-Regular Graphs with a Small Smallest Eigenvalue.
Electron. J. Comb.
Zhi Qiao, Yifan Jing, Jack H. Koolen
2019 J jnl
On 2-walk-regular graphs with a large intersection number c2.
Eur. J. Comb.
Zhi Qiao, Jongyook Park, Jack H. Koolen
2019 J jnl
On the Integrability of Strongly Regular Graphs.
Graphs Comb.
Jack H. Koolen, Masood Ur Rehman, Qianqian Yang
2019 J jnl
Open problems in the spectral theory of signed graphs.
CoRR
Francesco Belardo, Sebastian M. Cioaba, Jack H. Koolen, Jianfeng Wang
2019 J jnl
The polytopal structure of the tight-span of a totally split-decomposable metric.
Discret. Math.
Katharina T. Huber, Jack H. Koolen, Vincent Moulton
2019 J jnl
There Does Not Exist a Distance-Regular Graph with Intersection Array {80, 54, 12; 1, 6, 60}.
Graphs Comb.
Jack H. Koolen, Quaid Iqbal, Jongyook Park, Masood Ur Rehman
2018 J jnl
A spectral version of the Moore problem for bipartite regular graphs.
CoRR
Sebastian M. Cioaba, Jack H. Koolen, Hiroshi Nozaki
2018 J jnl
Addressing Johnson graphs, complete multipartite graphs, odd cycles and other graphs.
CoRR
Sebastian M. Cioaba, Brandon D. Gilbert, Jack H. Koolen, Brendan D. McKay
2018 J jnl
Edge-regular graphs with regular cliques.
Eur. J. Comb.
Gary R. W. Greaves, Jack H. Koolen
2018 J jnl
Graphs with three eigenvalues and second largest eigenvalue at most 1.
J. Comb. Theory B
Xi-Ming Cheng, Gary R. W. Greaves, Jack H. Koolen
2018 J jnl
Open problems in the spectral theory of signed graphs.
Art Discret. Appl. Math.
Francesco Belardo, Sebastian M. Cioaba, Jack H. Koolen, Jianfeng Wang
2018 J jnl
Partially metric association schemes with a multiplicity three.
J. Comb. Theory B
Edwin R. van Dam, Jack H. Koolen, Jongyook Park
2017 J jnl
A generalization of a theorem of Neumaier.
Des. Codes Cryptogr.
Xi-Ming Cheng, Jack H. Koolen
2017 J jnl
An Application of Hoffman Graphs for Spectral Characterizations of Graphs.
Electron. J. Comb.
Qianqian Yang, Aida Abiad, Jack H. Koolen
2017 J jnl
Light tails and the Hermitian dual polar graphs.
Des. Codes Cryptogr.
Jack H. Koolen, Zhi Qiao
2017 J jnl
Preface to the special issue dedicated to Andries E. Brouwer.
Des. Codes Cryptogr.
Aart Blokhuis, Edwin R. van Dam, Willem H. Haemers, Jack H. Koolen
2016 J jnl
2-Walk-Regular Dihedrants from Group-Divisible Designs.
Electron. J. Comb.
Zhi Qiao, Shao-Fei Du, Jack H. Koolen
2016 J jnl
A collection of results concerning electric resistance and simple random walk on distance-regular graphs.
Discret. Math.
Jack H. Koolen, Greg Markowsky
2016 J jnl
Biregular graphs with three eigenvalues.
Eur. J. Comb.
Xi-Ming Cheng, Alexander L. Gavrilyuk, Gary R. W. Greaves, Jack H. Koolen
2016 J jnl
Maximizing the Order of a Regular Graph of Given Valency and Second Eigenvalue.
SIAM J. Discret. Math.
Sebastian M. Cioaba, Jack H. Koolen, Hiroshi Nozaki, Jason R. Vermette
2015 J jnl
Edge-signed graphs with smallest eigenvalue greater than -2.
J. Comb. Theory B
Gary R. W. Greaves, Jack H. Koolen, Akihiro Munemasa, Yoshio Sano, Tetsuji Taniguchi
2015 J jnl
Large regular graphs with given valency and second eigenvalue.
CoRR
Sebastian M. Cioaba, Jack H. Koolen, Hiroshi Nozaki, Jason R. Vermette
2015 J jnl
Max-cut and extendability of matchings in distance-regular graphs.
CoRR
Sebastian M. Cioaba, Jack H. Koolen, Weiqiang Li
2015 J jnl
Optimal realizations of two-dimensional, totally-decomposable metrics.
Discret. Math.
Sven Herrmann, Jack H. Koolen, Alice Lesser, Vincent Moulton, Taoyang Wu
2015 J jnl
Some Results on the Eigenvalues of Distance-Regular Graphs.
Graphs Comb.
Sejeong Bang, Jack H. Koolen, Jongyook Park
2014 J jnl
Disconnecting strongly regular graphs.
Eur. J. Comb.
Sebastian M. Cioaba, Jack H. Koolen, Weiqiang Li
2014 J jnl
On fat Hoffman graphs with smallest eigenvalue at least -3.
Ars Math. Contemp.
Hye Jin Jang, Jack H. Koolen, Akihiro Munemasa, Tetsuji Taniguchi
2014 J jnl
Regular graphs with maximal energy per vertex.
J. Comb. Theory B
Edwin R. van Dam, Willem H. Haemers, Jack H. Koolen
2013 J jnl
A note on distance-regular graphs with a small number of vertices compared to the valency.
Eur. J. Comb.
Jack H. Koolen, Jongyook Park
2013 J jnl
Disconnecting strongly regular graphs.
CoRR
Sebastian M. Cioaba, Jack H. Koolen, Weiqiang Li
2013 J jnl
Distance-Regular Graphs with a Relatively Small Eigenvalue Multiplicity.
Electron. J. Comb.
Jack H. Koolen, Joohyung Kim, Jongyook Park
2013 J jnl
On electric resistances for distance-regular graphs.
Eur. J. Comb.
Jack H. Koolen, Greg Markowsky, Jongyook Park
2013 J jnl
There are only finitely many distance-regular graphs with valency k at least three, fixed ratio k
J. Comb. Theory B
Jongyook Park, Jack H. Koolen, Greg Markowsky
2012 J jnl
A relationship between the diameter and the intersection number c 2 for a distance-regular graph.
Des. Codes Cryptogr.
Jack H. Koolen, Jongyook Park
2012 J jnl
Distance-regular graphs with a
J. Comb. Theory A
Jack H. Koolen, Jongyook Park
2012 J jnl
Injective optimal realizations of finite metric spaces.
Discret. Math.
Jack H. Koolen, Alice Lesser, Vincent Moulton, Taoyang Wu
2012 J jnl
On a conjecture of Brouwer involving the connectivity of strongly regular graphs.
J. Comb. Theory A
Sebastian M. Cioaba, Kijung Kim, Jack H. Koolen
2011 J jnl
Classification of the family AT4(qs, q, q) of antipodal tight graphs.
J. Comb. Theory A
Aleksandar Jurisic, Jack H. Koolen
2011 J jnl
On a conjecture of Brouwer regarding the connectivity of strongly regular graphs
CoRR
Sebastian M. Cioaba, Kijung Kim, Jack H. Koolen
2010 J jnl
A lower bound for the spectral radius of graphs with fixed diameter.
Eur. J. Comb.
Sebastian M. Cioaba, Edwin R. van Dam, Jack H. Koolen, Jae-Ho Lee
2010 J jnl
Delsarte Set Graphs with Small
Graphs Comb.
Sejeong Bang, Akira Hiraki, Jack H. Koolen
2010 J jnl
Shilla distance-regular graphs.
Eur. J. Comb.
Jack H. Koolen, Jongyook Park
2009 J jnl
Bounds for the Hückel Energy of a Graph.
Electron. J. Comb.
Ebrahim Ghorbani, Jack H. Koolen, Jae Young Yang
2009 J jnl
Optimal realizations of generic five-point metrics.
Eur. J. Comb.
Jack H. Koolen, Alice Lesser, Vincent Moulton
2009 J jnl
The spectra of the local graphs of the twisted Grassmann graphs.
Eur. J. Comb.
Sejeong Bang, Tatsuya Fujisaki, Jack H. Koolen
2009 J jnl
The vertex-connectivity of a distance-regular graph.
Eur. J. Comb.
Andries E. Brouwer, Jack H. Koolen
2008 J jnl
On triangle-free distance-regular graphs with an eigenvalue multiplicity equal to the valency.
Eur. J. Comb.
Kris Coolsaet, Aleksandar Jurisic, Jack H. Koolen
2008 J jnl
Preface.
Discret. Math.
Sejeong Bang, Hyun Kwang Kim, Jack H. Koolen, Mitsugu Hirasaka, Sung Yell Song
2008 J jnl
Triangle-free distance-regular graphs with an eigenvalue multiplicity equal to their valency and diameter 3.
Eur. J. Comb.
Aleksandar Jurisic, Jack H. Koolen, Arjana Zitnik
2007 J jnl
Concerning the Relationship between Realizations and Tight Spans of Finite Metrics.
Discret. Comput. Geom.
Jack H. Koolen, Alice Lesser, Vincent Moulton
2006 J jnl
Combinatorics of lopsided sets.
Eur. J. Comb.
Hans-Jürgen Bandelt, Victor Chepoi, Andreas W. M. Dress, Jack H. Koolen
2005 J jnl
A generalization of an inequality of Brouwer-Wilbrink.
J. Comb. Theory A
Akira Hiraki, Jack H. Koolen
2005 J jnl
Delta additive and Delta ultra-additive maps, Gromov's trees, and the Farris transform.
Discret. Appl. Math.
Andreas W. M. Dress, Barbara R. Holland, Katharina T. Huber, Jack H. Koolen, Vincent Moulton, Jan Weyer-Menkhoff
2005 J jnl
Some Interlacing Results for the Eigenvalues of Distance-regular graphs.
Des. Codes Cryptogr.
Sejeong Bang, Jack H. Koolen
2005 J jnl
Triangle- and pentagon-free distance-regular graphs with an eigenvalue multiplicity equal to the valency.
J. Comb. Theory B
Aleksandar Jurisic, Jack H. Koolen, Stefko Miklavic
2004 J jnl
A Note on Regular Near Polygons.
Graphs Comb.
Akira Hiraki, Jack H. Koolen
2004 J jnl
The structure of spherical graphs.
Eur. J. Comb.
Jack H. Koolen, Vincent Moulton, Dragan Stevanovic
2003 J jnl
A Root Graph that is Locally the Line Graph of the Peterson Graph.
Discret. Math.
Andries E. Brouwer, Jack H. Koolen, Mikhail H. Klin
2003 J jnl
A bound for the number of columns l
Eur. J. Comb.
Sejeong Bang, Jack H. Koolen, Vincent Moulton
2003 J jnl
Addendum to "on line arrangements in the hyperbolic plane" [European J. Combin.23 (2002) 549-557].
Eur. J. Comb.
Andreas W. M. Dress, Jack H. Koolen, Vincent Moulton
2003 J jnl
Maximal Energy Bipartite Graphs.
Graphs Comb.
Jack H. Koolen, Vincent Moulton
2003 J jnl
Width and dual width of subsets in polynomial association schemes.
J. Comb. Theory A
Andries E. Brouwer, Chris D. Godsil, Jack H. Koolen, William J. Martin
2002 J jnl
Hyperbolic Bridged Graphs.
Eur. J. Comb.
Jack H. Koolen, Vincent Moulton
2002 J jnl
On Line Arrangements in the Hyperbolic Plane.
Eur. J. Comb.
Andreas W. M. Dress, Jack H. Koolen, Vincent Moulton
2002 J jnl
On a Conjecture of Bannai and Ito: There are Finitely Many Distance-regular Graphs with Degree 5, 6 or 7.
Eur. J. Comb.
Jack H. Koolen, Vincent Moulton
2001 J jnl
Maximal Energy Graphs.
Adv. Appl. Math.
Jack H. Koolen, Vincent Moulton
2000 J jnl
A Classification of the Six-point Prime Metrics.
Eur. J. Comb.
Jack H. Koolen, Vincent Moulton, Udo Tönges
2000 J jnl
A Local Approach to 1-Homogeneous Graphs.
Des. Codes Cryptogr.
Aleksandar Jurisic, Jack H. Koolen
2000 J jnl
Equilateral Dimension of the Rectilinear Space.
Des. Codes Cryptogr.
Jack H. Koolen, Monique Laurent, Alexander Schrijver
2000 J jnl
Nonexistence of some Antipodal Distance-regular Graphs of Diameter Four.
Eur. J. Comb.
Aleksandar Jurisic, Jack H. Koolen
1999 J jnl
Graphs which Locally Mirror the Hypercube Structure.
Inf. Process. Lett.
Sandi Klavzar, Jack H. Koolen, Henry Martyn Mulder
1998 J jnl
The Distance-regular Graphs with Intersection Number a
Comb.
Jack H. Koolen
1998 J jnl
The coherency index.
Discret. Math.
Jack H. Koolen, Vincent Moulton, Udo Tönges
1994 J jnl
Distance-regular Graphs the Distance Matrix of which has Only One Positive Eigenvalue.
Eur. J. Comb.
Jack H. Koolen, Sergey V. Shpectorov
1992 J jnl
A new condition for distance-regular graphs.
Eur. J. Comb.
Jack H. Koolen