An algorithm for the divisors of monic polynomials over a commutative ring

Gilmer and Heinzer proved that given a reduced ring R, a polynomial f divides a monic polynomial in R[X] if and only if there exists a direct sum decomposition of R = R₀ ⊕ … ⊕ R_m (m ≤ deg f), associated to a fundamental system of idempotents e₀, … , e_m, such that the component of f in each R_i[X] has degree coefficient which is a unit of R_i. We propose to give an algorithm to explicitly find such a decomposition. Moreover, we extend this result to divisors of doubly monic Laurent polynomials.     

The monic integer transfinite diameter

We study the problem of finding nonconstant monic integer polynomials, normalized by their degree, with small supremum on an interval . The monic integer transfinite diameter is defined as the infimum of all such supremums. We show that if has length , then .

We make three general conjectures relating to the value of for intervals of length less than . We also conjecture a value for where . We give some partial results, as well as computational evidence, to support these conjectures.

We define functions and , which measure properties of the lengths of intervals with on either side of . Upper and lower bounds are given for these functions.

We also consider the problem of determining when is a Farey interval. We prove that a conjecture of Borwein, Pinner and Pritsker concerning this value is true for an infinite family of Farey intervals.

     

The Dedekind-Mertens lemma and the contents of polynomials

We prove a sharpening of the Dedekind-Mertens Lemma relating the contents of two polynomials to the content of their product. We show that for a polynomial the integer in the Dedekind-Mertens Lemma may be replaced by the number of local generators of the content of . We also raise a question concerning the converse.

     

整系数多项式因式分解的一种新方法

利用整系数多项式与正有理数的对应 ,将多项式因式分解通过对真分数序列筛选的办法求得因式 ,给出了整系数多项式因式分解的一种新方法 .     

Tension polynomials of graphs

The tension polynomial F_G(k) of a graph G, evaluating the number of nowhere‐zero ?_k‐tensions in G, is the nontrivial divisor of the chromatic polynomial χ_G(k) of G, in that χ_G(k) = k^c(G)F_G(k), where c(G) denotes the number of components of G. We introduce the integral tension polynomial I_G(k), which evaluates the number of nowhere‐zero integral tensions in G with absolute values smaller than k. We show that 2^r(G)F_G(k)≥I_G(k)≥ (r(G)+1)F_G(k), where r(G)=|V(G)|?c(G), and, for every k>1, F_G(k+1)≥ F_G(k)˙k / (k?1) and I_G(k+1)≥I_G(k)˙k/(k?1). © 2002 Wiley Periodicals, Inc. J Graph Theory 40: 137–146, 2002     

Weighted lattice polynomials

We define the concept of weighted lattice polynomial functions as lattice polynomial functions constructed from both variables and parameters. We provide equivalent forms of these functions in an arbitrary bounded distributive lattice. We also show that these functions include the class of discrete Sugeno integrals and that they are characterized by a median-based decomposition formula.     

On series containing products of Legendre polynomials

Explicit formulas are established for infinite sums of products of three or four Legendre polynomials of nth order with coefficients 2n + 1; the series depends only the arguments of the polynomials and contains no other variables. We show that, for the product of three polynomials, the sum is inverse to the root of the product of four sine functions and, in the case of four polynomials, this expression additionally contains the elliptic integral K(k) as a multiplier. Analogs and particular cases are considered which allow one to compare the relationships proved in this note with results proved in various domains of mathematical physics and classical functional analysis.     

Convex linear combinations of sequences of monic orthogonal polynomials

For a sequence of monic orthogonal polynomials (SMOP), with respect to a positive measure supported on the unit circle, we obtain necessary and sufficient conditions on a SMOP in order that a convex linear combination with be a SMOP with respect to a positive measure supported on the unit circle.

     

The Drazin Inverse of a Morphism with a Sequence of (epic, monic) Factorizations

§ 1.Ｉｎｔｒｏｄｕｃｔｉｏｎ　Ｉｎ [1 ],ｔｈｅａｕｔｈｏｒｄｅｆｉｎｅｄａｃｃｕｒａｔｅｌｙｔｈｅＤｒａｚｉｎｉｎｖｅｒｓｅｏｆａｍｏｒｐｈｉｓｍ .Ｐｒｅｖｉｏｕｓｌｙ ,ｓｏｍｅｎｅｃｅｓｓａｒｙａｎｄｓｕｆｆｉｃｉｅｎｔｃｏｎｄｉｔｉｏｎｓｗｅｒｅｏｂｔａｉｎｅｄｆｏｒａｍｏｒｐｈｉｓｍｗｉｔｈ (ｅｐｉｃ ,ｍｏｎｉｃ)ｆａｃｔｏｒｉｚａｔｉｏｎｔｏｈａｖｅｔｈｅｇｒｏｕｐｉｎｖｅｒｓｅ (ｓｅｅ [2 ],Ｔｈｅｏｒｅｍ 1 )ａｎｄｔｈｅＤｒａｚｉｎｉｎｖｅｒｓｅｏｆａｍａｔｒｉｘｏｖｅｒｔｈｅｃｏｍｐ…     

On existence of common multiples of monic operator polynomials

A sufficient condition (in terms of spectral behaviour) for existence of common multiples of monic operator polynomials is given.     

The principal axis theorem for holomorphic functions

An algebraic approach to Rellich's theorem is given which states that any analytic family of matrices which is normal on the real axis can be diagonalized by an analytic family of matrices which is unitary on the real axis. We show that this result is a special version of a purely algebraic theorem on the diagonalization of matrices over fields with henselian valuations.

     

Stable factorizations of monic matrix polynomials and stable invariant subspaces

The stable factorizations of a monic matrix polynomial are characterized in terms of spectral properties. Proofs are based on the divisibility theory developed by I. Gohberg, P. Lancaster and L. Rodman. A large part of the paper is devoted to a detailed analysis of stable invariant subspaces of a matrix. The results are also used to describe all stable solutions of the operator Riccati equation.     

On some generalized Sister Celine's polynomials

Certain generalizations of Sister Celine's polynomials are given which include most of the known polynomials as their special cases. Besides, generating functions and integral representations of these generalized polynomials are derived and a relation between generalized Laguerre polynomials and generalized Bateman's polynomials is established.     

On the peripheral spectrum of monic operator polynomials with positive coefficients

I wish to thank R. Nagel for his guidance and suggestions in the preparation of this paper. Also, I would like to thank G. Greiner and F. Räbiger for many interesting and helpful discussions.     

Factorization of multivariate positive Laurent polynomials

Recently Dritschel proved that any positive multivariate Laurent polynomial can be factorized into a sum of square magnitudes of polynomials. We first give another proof of the Dritschel theorem. Our proof is based on the univariate matrix Fejér–Riesz theorem. Then we discuss a computational method to find approximates of polynomial matrix factorization. Some numerical examples will be shown. Finally we discuss how to compute nonnegative Laurent polynomial factorizations in the multivariate setting.