## A sequence of tests on derived polynomials to be strictly Hurwitz polynomials is shown to be equivalent to a given (typically real) polynomial having all its zeros in an open sector, symmetric with respect to the real axis, in the left half-plane. 7'he number of tests needed is at most 1 + [(In
Regions of polynomial root clustering
โ Scribed by T.A. Bickart; E.I. Jury
- Publisher
- Elsevier Science
- Year
- 1977
- Tongue
- English
- Weight
- 672 KB
- Volume
- 304
- Category
- Article
- ISSN
- 0016-0032
No coin nor oath required. For personal study only.
โฆ Synopsis
A criterion for root exclusion from a region composed as a union of elemental regions-discs and halfplanes-is established. Associated with each elemental region is a derived polynomial which must be by the criterion a strictly Hurwitz polynomial. The criterion is the basis for a root exclusion test, obtained by inuoking the equivalence of Ihe strict Hurwilr property of a polynomial and the positiviry of a set of inners [equivalently, Hurwitz] determinants associated with the polynomial.
๐ SIMILAR VOLUMES
## We restrict the discussion of root clustering (exclusion) to rational convex regions. A region in thisfamily is constructed as the intersection of an injinite number of halfplanes. The root clustering criterion inooloes the positiuity ofa set ofpolynomials with respect to the region's parameter
It is proved that the chromatic polynomial of a connected graph with n vertices and m edges has a root with modulus at least (m&1)ร(n&2); this bound is best possible for trees and 2-trees (only). It is also proved that the chromatic polynomial of a graph with few triangles that is not a forest has a
In general , not every set of values modulo n will be the set of roots modulo n of some polynomial . In this note , some characteristics of those sets which are root sets modulo a prime power are developed , and these characteristics are used to determine the number of dif ferent sets of integers wh