This paper analyzes circulant Johnson-Lindenstrauss (JL) embeddings which, as an important class of structured random JL embeddings, are formed by randomizing the column signs of a circulant matrix generated by a random vector. With the help of recent decoupling techniques and matrix-valued Bernstein inequalities, we obtain a new bound k = O(ǫ log(n)) for Gaussian circulant JL embeddings. Moreo...

The energy of a graph was introduced by Gutman in 1978 as the sum of the absolute values of the eigenvalues of its adjacency matrix. We study the energy of integral circulant graphs, also called gcd graphs. These are Cayley graphs on cyclic groups (i.e. there adjacency matrix is circulant) each of whose eigenvalues is an integer. Given an arbitrary prime power p, we determine all integral circu...

Explicit formulae for τ ′ r(L(p, q)) and τ(L(p, q)) are obtained for all L(p, q). There are three systems of invariants of Witten-type for closed oriented 3manifolds: 1. {τr(M), r ≥ 2; τ ′ r(M), r odd ≥ 3}, where τr was defined by Reshetikhin and Turaev [1], and τ ′ r was defined by Kirby-Melvin [2] 2. {Θr(M,A), r ≥ 1,whereA is a 2r-th primitive root of unity} defined by Blanchet, Habegger, Mas...

The main result is the “black dot algorithm” and its fast version for the construction of a new circulant preconditioner for Toeplitz matrices. This new preconditioner C is sought directly as a solution to one of possible settings of the approximation problem A ≈ C + R, where A is a given matrix and R should be a “low-rank” matrix. This very problem is a key to the analysis of superlinear conve...

Let ℱ and G be two t-uniform families of subsets over [k] = {1, 2, ..., k}, where |ℱ| |G|, let C the adjacency matrix bipartite graph whose vertices are in G, there is an edge between A ∈ B if only ∩ ≠ ∅. The pair (ℱ,G) q-almost cross intersecting every row column has exactly q zeros. We further restrict our attention to pairs that have a circulant intersection Cp, q, determined by vector with ...

Abstract. We construct the generalized version of covariant Z3-graded differential calculus introduced by one of us (R.K.) in [2], [3], and then extended to the case of arbitrary ZN grading in ([1], [5], [6]). Here our main purpose is to establish the recurrence formulae for the N-th power of covariant q-differential Dq = dq +A and to analyze more closely the particular case of q being an N th ...

Circulant matrices can be effective preconditioners for linear systems of equations with a Toeplitz matrix. Several approaches to construct such preconditioners have been described in the literature. This paper focuses on the superoptimal circulant preconditioners proposed by Tyrtyshnikov, and investigates a generalization obtained by allowing generalized circulant matrices. Numerical examples ...

An important aspect of cryptography with matrices is that given N ×N matrix P over a field F find a class of matrices G over F such that the associated doubly circulant matrix Gc is singular in order that the equation AGB = P in circulant matrices A,B has infinitely many solutions. The aim of this note is to present such a class of matrices G. We also present a direct method of finding the inve...

In this paper, we study norms of circulant matrices H = Circ(H 0 , H (k) 1 , . . . ,H (k) n−1) , H = Circ(H k , H (1) k , . . . ,H (n−1) k ) and r−circulant matrices Hr = Circr(H 0 ,H 1 , . . . ,H n−1) , Hr = Circr(H (0) k ,H (1) k , . . . ,H (n−1) k ) , where H (k) n denotes the n th hyperharmonic number of order r. Mathematics subject classification (2010): 15A60, 15B05, 11B99.

The distance energy of a graph G is a recently developed energy-type invariant, defined as the sum of absolute values of the eigenvalues of the distance matrix of G. There was a vast research for the pairs and families of non-cospectral graphs having equal distance energy, and most of these constructions were based on the join of graphs. A graph is called circulant if it is Cayley graph on the ...