Every vector space over a field K that has a finite spanning set has a finite basis: it is isomorphic to Kn for some n > 0. When we replace the scalar field K with a commutative ring A, it is no longer true that every A-module with a finite generating set has a basis: not all modules have bases. But when A is a PID, we get something nearly as good as that: (1) Every submodule of An has a basis ...

In the present paper, the author shows that if a homogeneous submodule M of the Bergman module La(Bd) satisfies PM − ∑ i MziPMM ∗ zi ≤ c N + 1 PM for some number c > 0, then there is a sequence {fj} of multipliers and a positive number c′ such that c′PM ≤ ∑ j Mfj M ∗ fj ≤ PM, i.e., M is approximately representable. The author also proves that approximately representable homogeneous submodules a...

Suppose R is a finite commutative ring of prime characteristic, A is a finite Rmodule, M := Z×N , and Φ is an R-linear cellular automaton on A. If μ is a Φ-invariant measure which is multiply σ-mixing in a certain way, then we show that μ must be the Haar measure on a coset of some submodule shift of A. Under certain conditions, this means μ must be the uniform Bernoulli measure on A. Let A be ...

We present an algorithm to compute the primary decomposition of a submodule N of the free module Z[x1, . . . , xn]. For this purpose we use algorithms for primary decomposition of ideals in the polynomial ring over the integers. The idea is to compute first the minimal associated primes of N , i.e. the minimal associated primes of the ideal Ann(Z[x1, . . . , xn]/N ) in Z[x1, . . . , xn] and the...

Here we consider all finite non-abelian 2-generator $p$-groups ($p$ an odd prime) of nilpotency class two and study the probability of having $n^{th}$-roots of them. Also we find integers $n$ for which, these groups are $n$-central.

We consider the following problem: For a system consisting of two submodules, the behavior of one submodule is known as well as the desired behavior S of the global system. What should be the behavior of the second submodule such that the behavior of the composition of the two submodules conforms to S ?-This problem has also been called "equation solving", and in the context of supervisory cont...

We initiate the study of 1-torsion of finite modules over two-sided noetherian semiperfect rings. In particular, we give a criterion for determining when the 1-torsion submodule contains minimal generators of the module. We also provide an explicit construction for a projective cover of the submodule generated by the torsion elements in the top of the module. Some of the obtained results hold w...

A new and conceptually simple procedure is derived for the computation of the maximal reachability submodule of a given submodule of the state space of a linear discrete time system over a Noethenian ring R. The procedure is effective if R is effective and if kernels and intersections can be computed. The procedure is compared with a rather different procedure by Assan e.a. published recently.

The object of this paper is to study the relationship between certain projective modules and their endomorphism rings. Specifically, the basic problem is to describe the projective modules whose endomorphism rings are (von Neumann) regular, local semiperfect, or left perfect. Call a projective module regular if every cyclic submodule is a direct summand. Thus a ring is a regular module if it is...

A labeling f on a graph G on n vertices is called a prime labeling if f is a bijection from the vertex set V (G) to {1, 2, · · · , n} such that f(x) and f(y) are coprime if x and y are adjacent. It was shown by Sundaram et al. [1] that the planar grid Pm × Pn has a prime labeling if m ≤ n and n is a prime. In this paper it is proved that the following grids have a prime labeling: (i) Pn+1 × Pn+...