منابع مشابه
Exponentially many supertrees
The amalgamation of leaf-labelled trees into a single supertree that displays each of the input trees is an important problem in classification. Clearly, there can be more than one (super) tree for a given set of input trees, in particular if a highly unresolved supertree exists. Here, we show (by explicit construction) that even if every supertree of a given collection of input trees is binary...
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Given a graph F , let st(F ) be the number of subdivisions of F , each with a different vertex set, which one can guarantee in a graph G in which every edge lies in at least t copies of F . In 1990, Tuza asked for which graphs F and large t, one has that st(F ) is exponential in a power of t. We show that, somewhat surprisingly, the only such F are complete graphs, and for every F which is not ...
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Let C be a code over q of length n and distance d = d(C): The (Hamming) distance distribution of the code is an (n + 1)-vector (A0 = 1; A1; : : : ; An); where Aw = Aw(C) := (]C) 1jf(x; x0) 2 C : d(x; x0) = wgj: Of course Aw = 0 if 1 w d 1: Let fCng be a family of binary linear codes of growing length n and let dn = d(Cn): G. Kalai and N. Linial [2] conjectured that for any such family the numbe...
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ژورنال
عنوان ژورنال: Applied Mathematics Letters
سال: 2002
ISSN: 0893-9659
DOI: 10.1016/s0893-9659(02)00054-x