Jack H. Koolen

ORCID

Publication Activity (10 Years)

Years Active: 1992-2024
Publications (10 Years): 54

Top Venues

Publications

Jack H. Koolen, Jae-Ho Lee, Shuang-Dong Li, Yun-Han Li, Xiaoye Liang, Ying-Ying Tan
On the (Non-)Existence of Tight Distance-Regular Graphs: a Local Approach. Electron. J. Comb. 31 (2) (2024)
Mamoon Abdullah, Brhane Gebremichel, Sakander Hayat, Jack H. Koolen
Distance-regular graphs with a few q-distance eigenvalues. Discret. Math. 347 (5) (2024)
Aida Abiad, Wouter Castryck, Maarten De Boeck, Jack H. Koolen, Sjanne Zeijlemaker
An infinite class of Neumaier graphs and non-existence results. J. Comb. Theory, Ser. A 193 (2023)
Zheng-Jiang Xia, Jae-Ho Lee, Jack H. Koolen
A New Feasibility Condition for the AT4 Family. Electron. J. Comb. 30 (2) (2023)
Ying-Ying Tan, Jack H. Koolen, Mengyue Cao, Jongyook Park
. Graphs Comb. 39 (1) (2023)
Yuanjiang Zhang, Xiaoye Liang, Jack H. Koolen
The 2-partially distance-regular graphs such that their second largest local eigenvalues are at most one. Discret. Math. 345 (3) (2022)
Mengyue Cao, Jack H. Koolen, Yen-Chi Roger Lin, Wei-Hsuan Yu
The Lemmens-Seidel conjecture and forbidden subgraphs. J. Comb. Theory, Ser. A 185 (2022)
Ying-Ying Tan, Jack H. Koolen, Mengyue Cao, Jongyook Park
. Graphs Comb. 38 (6) (2022)
Jack H. Koolen, Brhane Gebremichel
There Does Not Exist a Strongly Regular Graph with Parameters $(1911, 270, 105, 27)$. Electron. J. Comb. 29 (2) (2022)
Jack H. Koolen, Jae-Ho Lee, Ying-Ying Tan
Remarks on pseudo-vertex-transitive graphs with small diameter. Discret. Math. 345 (10) (2022)
Aida Abiad, Bart De Bruyn, Jozefien D'haeseleer, Jack H. Koolen
Neumaier graphs with few eigenvalues. Des. Codes Cryptogr. 90 (9) (2022)
Sebastian M. Cioaba, Jack H. Koolen, Masato Mimura, Hiroshi Nozaki, Takayuki Okuda
On the spectrum and linear programming bound for hypergraphs. Eur. J. Comb. 104 (2022)
Jack H. Koolen, Akihiro Munemasa, Atsuhiro Nakamoto, Katsuhiro Ota, Akira Saito
Preface to the special issue dedicated to Professors Eiichi Bannai and Hikoe Enomoto on their 75th birthdays. Graphs Comb. 37 (5) (2021)
Noga Alon, Sebastian M. Cioaba, Brandon D. Gilbert, Jack H. Koolen, Brendan D. McKay
Addressing Johnson Graphs, Complete Multipartite Graphs, Odd Cycles, and Random Graphs. Exp. Math. 30 (3) (2021)
Ying-Ying Tan, Xiaoye Liang, Jack H. Koolen
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. 28 (4) (2021)
Jack H. Koolen, Mengyue Cao, Qianqian Yang
Recent Progress on Graphs with Fixed Smallest Adjacency Eigenvalue: A Survey. Graphs Comb. 37 (4) (2021)
Gary R. W. Greaves, Jack H. Koolen, Jongyook Park
Augmenting the Delsarte bound: A forbidden interval for the order of maximal cliques in strongly regular graphs. Eur. J. Comb. 97 (2021)
Mengyue Cao, Jack H. Koolen, Akihiro Munemasa, Kiyoto Yoshino
Maximality of Seidel matrices and switching roots of graphs. Graphs Comb. 37 (5) (2021)
Sebastian M. Cioaba, Jack H. Koolen, Paul M. Terwilliger
-polynomial distance-regular graph. J. Comb. Theory, Ser. A 177 (2021)
Brhane Gebremichel, Mengyue Cao, Jack H. Koolen
Two characterizations of the grid graphs. Discret. Math. 344 (11) (2021)
Sebastian M. Cioaba, Jack H. Koolen, Masato Mimura, Hiroshi Nozaki, Takayuki Okuda
On the spectrum and linear programming bound for hypergraphs. CoRR (2020)
Ivan Guo, Jack H. Koolen, Greg Markowsky, Jongyook Park
On the nonexistence of pseudo-generalized quadrangles. Eur. J. Comb. 89 (2020)
Jack H. Koolen, Ying-Ying Tan, Zheng-Jiang Xia
-clique extension of the triangular graphs. Discuss. Math. Graph Theory 40 (2) (2020)
Zhi Qiao, Jack H. Koolen, Greg Markowsky
On the Cheeger constant for distance-regular graphs. J. Comb. Theory, Ser. A 173 (2020)
Zhi Qiao, Yifan Jing, Jack H. Koolen
Non-Bipartite Distance-Regular Graphs with a Small Smallest Eigenvalue. Electron. J. Comb. 26 (2) (2019)
Jack H. Koolen, Quaid Iqbal, Jongyook Park, Masood Ur Rehman
There Does Not Exist a Distance-Regular Graph with Intersection Array {80, 54, 12; 1, 6, 60}. Graphs Comb. 35 (6) (2019)
Sejeong Bang, Alexander L. Gavrilyuk, Jack H. Koolen
Distance-regular graphs without 4-claws. Eur. J. Comb. 80 (2019)
Sakander Hayat, Jack H. Koolen, Muhammad Riaz
A spectral characterization of the s-clique extension of the square grid graphs. Eur. J. Comb. 76 (2019)
Gary R. W. Greaves, Jack H. Koolen
Another construction of edge-regular graphs with regular cliques. Discret. Math. 342 (10) (2019)
Francesco Belardo, Sebastian M. Cioaba, Jack H. Koolen, Jianfeng Wang
Open problems in the spectral theory of signed graphs. CoRR (2019)
Alexander L. Gavrilyuk, Jack H. Koolen
. Comb. 39 (2) (2019)
Jack H. Koolen, Masood Ur Rehman, Qianqian Yang
On the Integrability of Strongly Regular Graphs. Graphs Comb. 35 (6) (2019)
Jack H. Koolen, Qianqian Yang, Jae Young Yang
A generalization of a theorem of Hoffman. J. Comb. Theory, Ser. B 135 (2019)
Katharina T. Huber, Jack H. Koolen, Vincent Moulton
The polytopal structure of the tight-span of a totally split-decomposable metric. Discret. Math. 342 (3) (2019)
Zhi Qiao, Jongyook Park, Jack H. Koolen
On 2-walk-regular graphs with a large intersection number c2. Eur. J. Comb. 80 (2019)
Edwin R. van Dam, Jack H. Koolen, Jongyook Park
Partially metric association schemes with a multiplicity three. J. Comb. Theory, Ser. B 130 (2018)
Francesco Belardo, Sebastian M. Cioaba, Jack H. Koolen, Jianfeng Wang
Open problems in the spectral theory of signed graphs. Art Discret. Appl. Math. 1 (2) (2018)
Sebastian M. Cioaba, Jack H. Koolen, Hiroshi Nozaki
A spectral version of the Moore problem for bipartite regular graphs. CoRR (2018)
Sebastian M. Cioaba, Brandon D. Gilbert, Jack H. Koolen, Brendan D. McKay
Addressing Johnson graphs, complete multipartite graphs, odd cycles and other graphs. CoRR (2018)
Gary R. W. Greaves, Jack H. Koolen
Edge-regular graphs with regular cliques. Eur. J. Comb. 71 (2018)
Xi-Ming Cheng, Gary R. W. Greaves, Jack H. Koolen
Graphs with three eigenvalues and second largest eigenvalue at most 1. J. Comb. Theory, Ser. B 129 (2018)
Aart Blokhuis, Edwin R. van Dam, Willem H. Haemers, Jack H. Koolen
Preface to the special issue dedicated to Andries E. Brouwer. Des. Codes Cryptogr. 84 (1-2) (2017)
Qianqian Yang, Aida Abiad, Jack H. Koolen
An Application of Hoffman Graphs for Spectral Characterizations of Graphs. Electron. J. Comb. 24 (1) (2017)
Jack H. Koolen, Zhi Qiao
Light tails and the Hermitian dual polar graphs. Des. Codes Cryptogr. 84 (1-2) (2017)
Xi-Ming Cheng, Jack H. Koolen
A generalization of a theorem of Neumaier. Des. Codes Cryptogr. 84 (1-2) (2017)
Jack H. Koolen, Greg Markowsky
A collection of results concerning electric resistance and simple random walk on distance-regular graphs. Discret. Math. 339 (2) (2016)
Sebastian M. Cioaba, Jack H. Koolen, Hiroshi Nozaki, Jason R. Vermette
Maximizing the Order of a Regular Graph of Given Valency and Second Eigenvalue. SIAM J. Discret. Math. 30 (3) (2016)
Xi-Ming Cheng, Alexander L. Gavrilyuk, Gary R. W. Greaves, Jack H. Koolen
Biregular graphs with three eigenvalues. Eur. J. Comb. 56 (2016)
Zhi Qiao, Shao-Fei Du, Jack H. Koolen
2-Walk-Regular Dihedrants from Group-Divisible Designs. Electron. J. Comb. 23 (2) (2016)
Sebastian M. Cioaba, Jack H. Koolen, Hiroshi Nozaki, Jason R. Vermette
Large regular graphs with given valency and second eigenvalue. CoRR (2015)
Sejeong Bang, Jack H. Koolen, Jongyook Park
Some Results on the Eigenvalues of Distance-Regular Graphs. Graphs Comb. 31 (6) (2015)
Sebastian M. Cioaba, Jack H. Koolen, Weiqiang Li
Max-cut and extendability of matchings in distance-regular graphs. CoRR (2015)
Gary R. W. Greaves, Jack H. Koolen, Akihiro Munemasa, Yoshio Sano, Tetsuji Taniguchi
Edge-signed graphs with smallest eigenvalue greater than -2. J. Comb. Theory, Ser. B 110 (2015)
Sven Herrmann, Jack H. Koolen, Alice Lesser, Vincent Moulton, Taoyang Wu
Optimal realizations of two-dimensional, totally-decomposable metrics. Discret. Math. 338 (8) (2015)
Edwin R. van Dam, Willem H. Haemers, Jack H. Koolen
Regular graphs with maximal energy per vertex. J. Comb. Theory, Ser. B 107 (2014)
Sebastian M. Cioaba, Jack H. Koolen, Weiqiang Li
Disconnecting strongly regular graphs. Eur. J. Comb. 38 (2014)
Hye Jin Jang, Jack H. Koolen, Akihiro Munemasa, Tetsuji Taniguchi
On fat Hoffman graphs with smallest eigenvalue at least -3. Ars Math. Contemp. 7 (1) (2014)
Jack H. Koolen, Jongyook Park
A note on distance-regular graphs with a small number of vertices compared to the valency. Eur. J. Comb. 34 (6) (2013)
Sebastian M. Cioaba, Jack H. Koolen, Weiqiang Li
Disconnecting strongly regular graphs. CoRR (2013)
Jack H. Koolen, Greg Markowsky, Jongyook Park
On electric resistances for distance-regular graphs. Eur. J. Comb. 34 (4) (2013)
Jongyook Park, Jack H. Koolen, Greg Markowsky
/k and large diameter. J. Comb. Theory, Ser. B 103 (6) (2013)
Jack H. Koolen, Joohyung Kim, Jongyook Park
Distance-Regular Graphs with a Relatively Small Eigenvalue Multiplicity. Electron. J. Comb. 20 (1) (2013)
Jack H. Koolen, Alice Lesser, Vincent Moulton, Taoyang Wu
Injective optimal realizations of finite metric spaces. Discret. Math. 312 (10) (2012)
Jack H. Koolen, Jongyook Park
A relationship between the diameter and the intersection number c 2 for a distance-regular graph. Des. Codes Cryptogr. 65 (1-2) (2012)
Sebastian M. Cioaba, Kijung Kim, Jack H. Koolen
On a conjecture of Brouwer involving the connectivity of strongly regular graphs. J. Comb. Theory, Ser. A 119 (4) (2012)
Jack H. Koolen, Jongyook Park
at least half the valency. J. Comb. Theory, Ser. A 119 (3) (2012)
Sebastian M. Cioaba, Kijung Kim, Jack H. Koolen
On a conjecture of Brouwer regarding the connectivity of strongly regular graphs CoRR (2011)
Aleksandar Jurisic, Jack H. Koolen
Classification of the family AT4(qs, q, q) of antipodal tight graphs. J. Comb. Theory, Ser. A 118 (3) (2011)
Sebastian M. Cioaba, Edwin R. van Dam, Jack H. Koolen, Jae-Ho Lee
A lower bound for the spectral radius of graphs with fixed diameter. Eur. J. Comb. 31 (6) (2010)
Sejeong Bang, Akira Hiraki, Jack H. Koolen
. Graphs Comb. 26 (2) (2010)
Jack H. Koolen, Jongyook Park
Shilla distance-regular graphs. Eur. J. Comb. 31 (8) (2010)
Ebrahim Ghorbani, Jack H. Koolen, Jae Young Yang
Bounds for the Hückel Energy of a Graph. Electron. J. Comb. 16 (1) (2009)
Andries E. Brouwer, Jack H. Koolen
The vertex-connectivity of a distance-regular graph. Eur. J. Comb. 30 (3) (2009)
Sejeong Bang, Tatsuya Fujisaki, Jack H. Koolen
The spectra of the local graphs of the twisted Grassmann graphs. Eur. J. Comb. 30 (3) (2009)
Jack H. Koolen, Alice Lesser, Vincent Moulton
Optimal realizations of generic five-point metrics. Eur. J. Comb. 30 (5) (2009)
Aleksandar Jurisic, Jack H. Koolen, Arjana Zitnik
Triangle-free distance-regular graphs with an eigenvalue multiplicity equal to their valency and diameter 3. Eur. J. Comb. 29 (1) (2008)
Sejeong Bang, Hyun Kwang Kim, Jack H. Koolen, Mitsugu Hirasaka, Sung Yell Song
Preface. Discret. Math. 308 (14) (2008)
Kris Coolsaet, Aleksandar Jurisic, Jack H. Koolen
On triangle-free distance-regular graphs with an eigenvalue multiplicity equal to the valency. Eur. J. Comb. 29 (5) (2008)
Jack H. Koolen, Alice Lesser, Vincent Moulton
Concerning the Relationship between Realizations and Tight Spans of Finite Metrics. Discret. Comput. Geom. 38 (3) (2007)
Hans-Jürgen Bandelt, Victor Chepoi, Andreas W. M. Dress, Jack H. Koolen
Combinatorics of lopsided sets. Eur. J. Comb. 27 (5) (2006)
Akira Hiraki, Jack H. Koolen
A generalization of an inequality of Brouwer-Wilbrink. J. Comb. Theory, Ser. A 109 (1) (2005)
Aleksandar Jurisic, Jack H. Koolen, Stefko Miklavic
Triangle- and pentagon-free distance-regular graphs with an eigenvalue multiplicity equal to the valency. J. Comb. Theory, Ser. B 94 (2) (2005)
Sejeong Bang, Jack H. Koolen
Some Interlacing Results for the Eigenvalues of Distance-regular graphs. Des. Codes Cryptogr. 34 (2-3) (2005)
Andreas W. M. Dress, Barbara R. Holland, Katharina T. Huber, Jack H. Koolen, Vincent Moulton, Jan Weyer-Menkhoff
Delta additive and Delta ultra-additive maps, Gromov's trees, and the Farris transform. Discret. Appl. Math. 146 (1) (2005)
Jack H. Koolen, Vincent Moulton, Dragan Stevanovic
The structure of spherical graphs. Eur. J. Comb. 25 (2) (2004)
Akira Hiraki, Jack H. Koolen
A Note on Regular Near Polygons. Graphs Comb. 20 (4) (2004)
Andries E. Brouwer, Jack H. Koolen, Mikhail H. Klin
A Root Graph that is Locally the Line Graph of the Peterson Graph. Discret. Math. 264 (1-3) (2003)
Jack H. Koolen, Vincent Moulton
Maximal Energy Bipartite Graphs. Graphs Comb. 19 (1) (2003)
Andries E. Brouwer, Chris D. Godsil, Jack H. Koolen, William J. Martin
Width and dual width of subsets in polynomial association schemes. J. Comb. Theory, Ser. A 102 (2) (2003)
Andreas W. M. Dress, Jack H. Koolen, Vincent Moulton
Addendum to "on line arrangements in the hyperbolic plane" [European J. Combin.23 (2002) 549-557]. Eur. J. Comb. 24 (3) (2003)
Sejeong Bang, Jack H. Koolen, Vincent Moulton
in the intersection array of a distance-regular graph. Eur. J. Comb. 24 (7) (2003)
Andreas W. M. Dress, Jack H. Koolen, Vincent Moulton
On Line Arrangements in the Hyperbolic Plane. Eur. J. Comb. 23 (5) (2002)
Jack H. Koolen, Vincent Moulton
Hyperbolic Bridged Graphs. Eur. J. Comb. 23 (6) (2002)
Jack H. Koolen, Vincent Moulton
On a Conjecture of Bannai and Ito: There are Finitely Many Distance-regular Graphs with Degree 5, 6 or 7. Eur. J. Comb. 23 (8) (2002)
Jack H. Koolen, Vincent Moulton
Maximal Energy Graphs. Adv. Appl. Math. 26 (1) (2001)
Jack H. Koolen, Vincent Moulton, Udo Tönges
A Classification of the Six-point Prime Metrics. Eur. J. Comb. 21 (6) (2000)
Aleksandar Jurisic, Jack H. Koolen
Nonexistence of some Antipodal Distance-regular Graphs of Diameter Four. Eur. J. Comb. 21 (8) (2000)
Jack H. Koolen, Monique Laurent, Alexander Schrijver
Equilateral Dimension of the Rectilinear Space. Des. Codes Cryptogr. 21 (1/3) (2000)
Aleksandar Jurisic, Jack H. Koolen
A Local Approach to 1-Homogeneous Graphs. Des. Codes Cryptogr. 21 (1/3) (2000)
Sandi Klavzar, Jack H. Koolen, Henry Martyn Mulder
Graphs which Locally Mirror the Hypercube Structure. Inf. Process. Lett. 71 (2) (1999)

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Publication Activity (10 Years)

Top Topics

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Jack H. Koolen