We study the decidability of three well-known problems related to integer matrix multiplication: Mortality (M), Zero in the Left-Upper Corner (Z), and Zero in the Right-Upper Corner (R). Let d and k be positive integers. Define M(k) as the following special case of the Mortality problem: given a set X of d-by-d integer matrices such that the cardinality of X is not greater than k, decide whethe...

We study the linking numbers in a rational homology 3-sphere and in the infinite cyclic cover of the complement of a knot. They take values in Q and inQ(Z[t, t−1]) respectively, where Q(Z[t, t−1]) denotes the quotient field of Z[t, t−1]. It is known that the modulo-Z linking number in the rational homology 3-sphere is determined by the linking matrix of the framed link and that the modulo-Z[t, ...

A full-rank lattice L in R is a discrete subgroup of R which is the set of all integer linear combinations of n-linearly independent vectors, say b1, · · · ,bn i.e., L = { ∑n i=1 zibi | z1, · · · , zn ∈ Z}. The matrix B = [b1, · · · ,bn] is called the basis of the lattice and the matrix Q = B′B is called a Gram matrix of the lattice. A lattice is integral if its Gram matrix has only integer ent...

We introduce the notions of matrix–valued wavelet set and matrix– valued multiresolution analysis (A-MMRA) associated with a fixed dilation given by an expansive linear map A : R → R, d ≥ 1 such that A(Z) ⊂ Z, in a matrix–valued function space L(R,C), n ≥ 1. These are generalizations of the corresponding notions defined by Xia and Suter in 1996 for the case where d = 1 and A is the dyadic dilat...

Here, we will consider one approach for extending the ideas underlying the least-squares algorithm we discussed in class to non-tall matrices. Let A ∈ Rn×d matrix, where both n and d are large, and where rank(A) = k exactly, and let B ∈ Rn×t. Consider the problem minX∈Rn×t‖AX −B‖, where ‖ · ‖ is a unitarily-invariant matrix norm. The solution to this problem is Xopt = AB, and here we consider a...

A well-known result of Lyapunov on continuous linear systems asserts that a real square matrix A is positive stable if and only if for some symmetric positive definite matrix X, AX + XA is also positive definite. A recent result of Moldovan-Gowda says that a Z-matrix A is positive stable if and only if for some symmetric strictly copositive matrix X, AX + XA is also strictly copositive. In this...

Let A k ; k 0, be a sequence of m m nonnegative matrices and let A(z) = P 1 k=0 A k z k be such that A(1) is an irreducible stochastic matrix. The unique power-bounded solution of the nonlinear matrix equation G = P 1 k=0 A k G k has been shown to play a key role in the analysis of Markov chains of M/G/1 type. Assuming that the matrix A(z) is rational, we show that the solution of this matrix e...

If a matrix .4 transforms a sequence {z„} into the sequence {z, A is said to be regular. The well known necessary and sufficient conditions for A to be regular are1 (a) X^-i |g»,*| Wo, (b) limn^oo an,k = 0 for every fixed fe, (c) XXi a»j»«A»—»1 as w-»°o. It is known2 that if a regular matrix s...

The knowledge of the partition function, Z, of a system of particles adsorbed on a surface is all that is required to determine the occupational characteristics of the adsorbates and the thermodynamic properties of the system. The surface considered is a terrace or a nanotube of arbitrary periodic lattice geometry, L atomic sites in length, and M' sites in the width of the terrace or in the nor...

In this paper, we apply the discrete wavelet transform (DWT) and the discrete wavelet packet transform (DWPT) with the Daubechies wavelet of order 16 to effectively solve for the electromagnetic scattering from a one-dimensional inhomogeneous slab. Methods based on the excitation vector and the [Z] matrix are utilized to sparsify an MoM matrix. As we observed, there are no much high frequency c...