Displaying similar documents to “Apollonius' contact problem in n -space in view of enumerative geometry.”

On the weak non-defectivity of veronese embeddings of projective spaces

Edoardo Ballico (2005)

Open Mathematics

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Fix integers n, x, k such that n≥3, k>0, x≥4, (n, x)≠(3, 4) and k(n+1)<(nn+x). Here we prove that the order x Veronese embedding ofP n is not weakly (k−1)-defective, i.e. for a general S⊃P n such that #(S) = k+1 the projective space | I 2S (x)| of all degree t hypersurfaces ofP n singular at each point of S has dimension (n/n+x )−1− k(n+1) (proved by Alexander and Hirschowitz) and a general F∈| I 2S (x)| has an ordinary double point at each P∈ S and Sing (F)=S.

Value-peaks of permutations.

Bouchard, Pierre, Chang, Hungyung, Ma, Jun, Yeh, Jean, Yeh, Yeong-Nan (2010)

The Electronic Journal of Combinatorics [electronic only]

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Restricted partitions and q-Pell numbers

Toufik Mansour, Mark Shattuck (2011)

Open Mathematics

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In this paper, we provide new combinatorial interpretations for the Pell numbers p n in terms of finite set partitions. In particular, we identify six classes of partitions of size n, each avoiding a set of three classical patterns of length four, all of which have cardinality given by p n. By restricting the statistic recording the number of inversions to one of these classes, and taking it jointly with the statistic recording the number of blocks, we obtain a new polynomial generalization...

On coefficient inequalities in the Carathéodory class of functions

Adam Lecko (2000)

Annales Polonici Mathematici

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Some inequalities are proved for coefficients of functions in the class P(α), where α ∈ [0,1), of functions with real part greater than α. In particular, new inequalities for coefficients in the Carathéodory class P(0) are given.