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JCT
2006
83views more  JCT 2006»
13 years 11 months ago
The mathematics of Bruce Rothschild
A review is given of some of the mathematical research of Bruce Rothschild, emphasizing his results in combinatorial theory, especially that part known as Ramsey Theory. Special em...
Neil Hindman
JCT
2006
81views more  JCT 2006»
13 years 11 months ago
Cycle double covers and spanning minors I
Roland Häggkvist, Klas Markström
JCT
2006
67views more  JCT 2006»
13 years 11 months ago
On the coexistence of conference matrices and near resolvable 2-(2k+1, k, k-1) designs
We show that a near resolvable 2-(2k + 1, k, k - 1) design exists if and only if a conference matrix of order 2k + 2 does. A known result on conference matrices then allows us to ...
Malcolm Greig, Harri Haanpää, Petteri Ka...
JCT
2006
89views more  JCT 2006»
13 years 11 months ago
Asymptotic enumeration of sparse 0-1 matrices with irregular row and column sums
Let s = (s1, . . . , sm) and t = (t1, . . . , tn) be vectors of non-negative integervalued functions with equal sum S = m i=1 si = n j=1 tj. Let N(s, t) be the number of m
Catherine S. Greenhill, Brendan D. McKay, Xiaoji W...
JCT
2006
54views more  JCT 2006»
13 years 11 months ago
Spectral estimates for Abelian Cayley graphs
We give two short proofs that for fixed d, a d-regular Cayley graph on an Abelian group of order n has second eigenvalue bounded below by d - O(dn-4/d), where the implied constant...
Joel Friedman, Ram Murty, Jean-Pierre Tillich
JCT
2006
82views more  JCT 2006»
13 years 11 months ago
On Rado's Boundedness Conjecture
We prove that Rado's Boundedness Conjecture from Richard Rado's 1933 famous dissertation Studien zur Kombinatorik is true if it is true for homogeneous equations. We the...
Jacob Fox, Daniel J. Kleitman
JCT
2006
46views more  JCT 2006»
13 years 11 months ago
Optimal tristance anticodes in certain graphs
For z1, z2, z3 Zn, the tristance d3(z1, z2, z3) is a generalization of the L1-distance on Zn to a quantity that reflects the relative dispersion of three points rather than two. ...
Tuvi Etzion, Moshe Schwartz, Alexander Vardy
JCT
2006
73views more  JCT 2006»
13 years 11 months ago
Colouring lines in projective space
Let V be a vector space of dimension v over a field of order q. The q-Kneser graph has the kdimensional subspaces of V as its vertices, where two subspaces and are adjacent if and...
Ameera Chowdhury, Chris D. Godsil, Gordon F. Royle
JCT
2006
134views more  JCT 2006»
13 years 11 months ago
MacLane's planarity criterion for locally finite graphs
MacLane's planarity criterion states that a finite graph is planar if and only if its cycle space has a basis B such that every edge is contained in at most two members of B....
Henning Bruhn, Maya Jakobine Stein