Cheyne Homberger 1
1Department of Mathematics University of Florida Gainesville, FL
Abstract:

We consider the problem of packing fixed-length patterns into a permutation, and develop a connection between the number of large patterns and the number of bonds in a permutation. Improving upon a result of Kaplansky and Wolfowitz, we obtain exact values for the expectation and variance for the number of large patterns in a random permutation. Finally, we are able to generalize the idea of bonds to obtain results on fixed-length patterns of any size, and present a construction that maximizes the number of patterns of a fixed size.

Chak-On Chow 1, Toufik Mansour2
1Department of Mathematics and Information Technology Hong Kong Institute of Education, 10 Lo Ping Road, Tai Po, New Territories, Hong Kong
2 Department of Mathematics University of Haifa, 31905 Haifa, Israel
Abstract:

We present in this work results on some distributions of permutation statistics of random elements of the wreath product \( G_{r,n} = C_r \wr S_n \). We consider the distribution of the descent number, the flag major index, the excedance, and the number of fixed points, over the whole group \( G_{r,n} \), or over the subclasses of derangements and involutions. We compute the mean, variance and moment generating function, and establish the asymptotic distributions of these statistics.

Brian Cook1, Ákos Magyar2
1Department of Mathematics, The University of British Columbia, Vancouver, BC, V6T1Z2, Canada
2Department of Mathematics, University of British Columbia, Vancouver, B.C. V6T 1Z2, Canada
Abstract:

Let \( A \) be a subset of \( \mathbb{F}_p^n \), the \( n \)-dimensional linear space over the prime field \( \mathbb{F}_p \), of size at least \( \delta N \) (\( N = p^n \)), and let \( S_v = P^{-1}(v) \) be the level set of a homogeneous polynomial map \( P : \mathbb{F}_p^n \to \mathbb{F}_p^R \) of degree \( d \), for \( v \in \mathbb{F}_p^R \). We show that, under appropriate conditions, the set \( A \) contains at least \( c N|S| \) arithmetic progressions of length \( l \leq d \) with common difference in \( S_v \), where \( c \) is a positive constant depending on \( \delta \), \( l \), and \( P \). We also show that the conditions are generic for a class of sparse algebraic sets of density \( \approx N^{-\gamma} \).

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