A Combinatorial Object
Hadamard matrix of order 428
Description: A Hadamard matrix is a square matrix
whose entries are either +1 (white pixels) or -1 (black pixels) and
whose rows are mutually orthogonal. A Hadamard matrix of order 428, the smallest unknown order
of Hadamard matrices before June 2004, was built by Hadi Kharaghani and Behruz Tayfeh-Rezaie.
Since June 2004, the order 668 has been the smallest multiple of 4 for which no Hadamard matrix
is yet known.
It is conjectured that examples of order 4n exist for all n.
Publications

On a Question of Erdos and Faudree on the size Ramsey Numbers
SIAM J. Discrete Math. (to appear)
More Info
R. Javadi (Joint with X. Niu and H. Cao),
The spectrum for large sets of $(3,\lambda$)-GDDs of type $g^{u}$
J. Combin. Des. (to appear)
More Info
M. Alishahi,
A generalization of Gale's lemma
J. Graph Theory 88(2018), 337-346
More Info
M. Alishahi,
On the random version of the Erdos matching conjecture
Discrete Appl. Math. (to appear)
More Info
M. R. Oboudi,
Majorization and the spectral radius of starlike trees
J. Comb. Optim. 36(2018), 121-129
More Info
M. R. Oboudi,
Some results on the independence polynomial of unicycle graphs
Discussiones Mathematicae Graph Theory 38(2018), 515-524
More Info
A. Abdollahi (Joint with F. Jafari),
Zero divisor and unit elements with supports of size 4 in group algebras of torsion-free groups
Comm. Algebra (to appear)
More Info
G.R. Omidi,
On a Question of Erdos and Faudree on the size Ramsey Numbers
SIAM J. Discrete Math. (to appear)
More Info
A. Davoodi (Joint with E. Gyori and A. Methuku),
An Erd\H{o}s-Gallai type theorem for uniform hypergraphs
European J. Combin. 69(2018), 159-162
More Info
A. Mohammadian and B. Tayfeh-Rezaie,
Hadamard matrices with few distinct types
Linear Multilinear Algebra (to appear)
More Info
M. R. Oboudi,
On the eigenvalues and spectral radius of starlike trees
Aequat. Math. (2018), DOI: 10.1007/s00010-017-0533-4
More Info
A. Mohammadian and B. Tayfeh-Rezaie,
Star saturation number of random graphs
Discrete Math. 341(2018), 1166-1170
More Info
H. Hajiabolhassan (Joint with M. Alishahi),
Chromatic number of random kneser hypergraphs
J. Combin. Theory Ser. A (to appear)
More Info
M. R. Oboudi,
On the difference between the spectral radius and the maximum degree of graphs
Algebra Discrete Math. 24(2017), 302-307
More Info
G.R. Omidi and M. Shahsiah,
Diagonal Ramsey numbers of loose cycles in uniform hypergraphs
SIAM J. Discrete Math. (to appear)
More Info

footer