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Quasi-symmetric designs related to the triangular graph
W.J. Coster,W.H. Haemers +1 more
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Three-Class Association Schemes
TL;DR: In this paper, a list of feasible parameter sets on at most 100 vertices is generated for three-class association schemes with four distinct eigenvalues, and necessary conditions for existence are given.
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Graphs with Few Eigenvalues
TL;DR: A graph with only one eigenvalue (for A, L, or Q) is edgeless as mentioned in this paper, and a connected graph with two distinct adjacency eigenvalues is complete.
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Conditions for the Parameters of the Block Graph of Quasi-Symmetric Designs
TL;DR: A quasi-symmetric design (QSD) is a 2-$(v,k,\lambda) design with intersection numbers $x and $y$ with $x 2(x+2)$ or if it is a $3$-design is proven.
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Non-derivable strongly regular graphs from quasi-symmetric designs
TL;DR: It is shown that the pseudo Latin square graph L 5 ( n ) , n ?
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Conditions for Singular Incidence Matrices
TL;DR: In this paper, the Bruck-Ryser-Chowla theorem was used to obtain non-existence conditions for self-dual generalised polygons, semi-regular square divisible designs and distance-regular graphs.
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Sphere packings I
TL;DR: A program to prove the Kepler conjecture on sphere packings is described and it is shown that every Delaunay star that satisfies a certain regularity condition satisfies the conjecture.
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Designs, graphs, codes, and their links
Peter J. Cameron,J.H. van Lint +1 more
TL;DR: The authors have considerably reworked and expanded their earlier successful books on designs, graphs and codes, into an invaluable textbook that is accessible to any student with a background of undergraduate algebra.