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Motivated by the problem of zero-error broadcasting, we introduce a new notion of graph capacity, termed $rho$-capacity, that generalizes the Shannon capacity of a graph. We derive upper and lower bounds on the $rho$-capacity of arbitrary graphs, and provide a Lovasz-type upper bound for regular graphs. We study the behavior of the $rho$-capacity under two graph operations: the strong product and the disjoint union. Finally, we investigate the connection between the structure of a graph and its $rho$-capacity.
We prove an upper bound on the Shannon capacity of a graph via a linear programming variation. We show that our bound can outperform both the Lovasz theta number and the Haemers minimum rank bound. As a by-product, we also obtain a new upper bound on the broadcast rate of Index Coding.
Maximum distance separable (MDS) codes are very important in both theory and practice. There is a classical construction of a family of $[2^m+1, 2u-1, 2^m-2u+3]$ MDS codes for $1 leq u leq 2^{m-1}$, which are cyclic, reversible and BCH codes over $ma
Consider two sequences of $n$ independent and identically distributed fair coin tosses, $X=(X_1,ldots,X_n)$ and $Y=(Y_1,ldots,Y_n)$, which are $rho$-correlated for each $j$, i.e. $mathbb{P}[X_j=Y_j] = {1+rhoover 2}$. We study the question of how larg
The determination of weight distribution of cyclic codes involves evaluation of Gauss sums and exponential sums. Despite of some cases where a neat expression is available, the computation is generally rather complicated. In this note, we determine t
The codewords of weight $10$ of the $[42,21,10]$ extended binary quadratic residue code are shown to hold a design of parameters $3-(42,10,18).$ Its automorphism group is isomorphic to $PSL(2,41)$. Its existence can be explained neither by a transitivity argument, nor by the Assmus-Mattson theorem.