Evaluations of Parameters for the Optimization of S.S.O.R. and A.D.I. Preconditioning

The main goal of this paper is to give two ways to estimate the needed parameters in order to obtain the condition number of S.S.O.R. preconditioned matrices, namely, the algebraic matricial formulation of convexity Riesz theorem and the tridiagonal Fourier analysis. The improvement with respect to Axelsson's approach is explicitly given. Estimations of the condition number in the case of A.D.I. preconditioning is also considered.     

The E.E.C. and the development of O.R.

The growth of the E.E.C. has brought about a change in the scale of many organizational problems and a change in the ways that they can be tackled. Accordingly it is plausible that the techniques of O.R. should develop in response to these changes. This paper examines some desirable developments and suggests ways in which they might be achieved by adapting methods devised in other fields for similar problems.     

On the r.e. predecessors of d.r.e. degrees

Let d be a Turing degree containing differences of recursively enumerable sets (d.r.e.sets) and R[d] be the class of less than d r.e. degrees in whichd is relatively enumerable (r.e.). A.H.Lachlan proved that for any non-recursive d.r.e. d R[d] is not empty. We show that the r.e. degree defined by Lachlan for a d.r.e.set d is just the minimum degree in which D is r.e. Then we study for a given d.r.e. degree d class R[d] and show that there exists a d.r.e.d such that R d] has a minimum element 0. The most striking result of the paper is the existence of d.r.e. degrees for which R[d] consists of one element. Finally we prove that for some d.r.e. d R[d] can be the interval [a,b] for some r.e. degrees a,b, a b d. Received: 17 January 1996     

Optimization of the Relaxation Parameter for S.S.O.R. and A.D.I. Preconditioning

We present and compare several approaches for the optimization of the relaxation parameter both for A.D.I. and S.S.O.R. basic iteration and preconditioning conjugate gradient method. For each kind of preconditioning a detailed link between estimates of the spectral radius of the iteration matrix and of the condition number resulting from preconditioning is proposed. It allows to choose the best approach in order to obtain the optimal relaxation parameter and the corresponding optimal estimates either of the spectral radius of the iteration matrix and of the resulting condition mumber of the S.S.O.R. and A.D.I. preconditioning.     

On a conjecture of W.E. Clark and M.E.H. Ismail

W.E. Clark and M.E.H. Ismail conjectured the inequality

Infima of d.r.e. degrees

Lachlan observed that the infimum of two r.e. degrees considered in the r.e. degrees coincides with the one considered in the D₂⁰{\Delta_2^0} degrees. It is not true anymore for the d.r.e. degrees. Kaddah proved in (Ann Pure Appl Log 62(3):207–263, 1993) that there are d.r.e. degrees a, b, c and a 3-r.e. degree x such that a is the infimum of b, c in the d.r.e. degrees, but not in the 3-r.e. degrees, as a < x < b, c. In this paper, we extend Kaddah’s result by showing that such a structural difference occurs densely in the r.e. degrees. Our result immediately implies that the isolated 3-r.e. degrees are dense in the r.e. degrees, which was first proved by LaForte.     

逆p·n·p·矩阵的表征

一个n阶实方阵A,若其各阶主子式皆非正,则称A为p.n.p.矩阵,记作A∈PNP;特别地,若A∈NP且各阶主子式皆负,则称A为p.n.矩阵,记作A∈PN进一步,若n阶实方阵A非奇异,且A^-1∈PNP,则称A为逆p.n.p.矩阵,记作A∈IPNP;特别地,若A^-1∈PN,则称A为逆p.n.矩阵,记作A∈IPN。     

Monotone factors of I.I.D. processes

LetB(p) andB(q) be Bernoulli shifts on {0, 1,...,d - 1}^ℤ. Ifh(p)>h(q), it is a classical theorem of Sinai that there is a factor map takingB(p) toB(q). If, in addition,p stochastically dominatesq, we can ask whether there is such a factor map ϕ which is monotone: ϕ(x) _i≤x_i for each coordinatei of almost every pointx. Here we show that there is a monotone finitary code fromB(p) toB(q) in the case whereB(q) is a shift on two symbols.     

Temperature dependence of S.C.L.C. in anthracene crystals

Zusammenfassung Aus der Temperaturabhängigkeit des Löcherstroms in Anthrazen-Einkristallen wird die Aktivierungsenergie bei verschiedenen Dunkelstromwerten gemessen. Die Aktivierungsenergien liegen zwischen 0,65 eV und 0,95 eV für Ströme von 10^–10 bzw. 10^–12 Ampère bei Zimmertemperatur.Ferner wird für mehrere Temperaturwerte die Aktivierung der in Haftstellen sitzenden Ladungsträger mit Hilfe von Licht verschiedener Intensität untersucht.     

p.n.p.矩阵的一些性质

一个n阶实方阵若其各阶主子式皆非正,则称为部分非正阵,简写作p.n.p.矩阵.特别地,各阶主子式皆负的p.n.p.矩阵称为部分负矩阵,简写为p.n.矩阵。文[1]、[5]讨论了p.n.p.矩阵的谱性质。本文在[5]的基础上讨论了p.n.p.矩阵的若干性质,并给出p.n.p.矩阵特征值的某些估计式。 引理1 设A=(A_(ij)_n×n为一p.n.p.矩阵,则A的特征值之实部不全为负(n≥2)。 证 设λ_1,λ_2,…,λ_n为A的全部特征值。假定A的每一特征值之实部皆为负。分两种情     

The Influence of P. A. Florensky on N. N. Luzin

The study of the early history of the Moscow school of the theory of functions has been greatly enhanced by the discovery of correspondence between one of its founders, N. N. Luzin, and the priest, theologian, philosopher, and scientist P. A. Florensky. The correspondence reveals that Luzin experienced a profound spiritual crisis in 1905 when his materialist worldview collapsed. This crisis continued for three years and was finally resolved when Luzin had a decisive encounter with the religious philosophy of Florensky. After this, Luzin's interest in mathematics gradually revived until he was able, by 1909, to commit himself to a career in mathematics.Copyright 1998 Academic Press.Les études concernant l'histoire des débuts de l'école moscovite de la théorie des functions ont été grandement éclairées par la découverte d'une correspondance entre l'un de ses fondateurs, N. N. Luzin, et P. A. Florenski, un prêtre, théologien, philosophe, et savant. Cette correspondance révèle que Luzin a traversé une crise spirituelle profonde à partir de 1905, lorsque sa perspective matérialiste du monde s'est effondrée. Cette crise a duré trois ans, et a trouvé sa résolution dans la rencontre décisive de Luzin avec la philosophie religieuse de Florenski. Par la suite, l'intérêt de Luzin pour les mathématiques s'est progressivement ravivé, jusqu'à ce qu'il soit en mesure de décider, en 1909, de consacrer sa vie aux mathématiques.Copyright 1998 Academic Press.[formula]Copyright 1998 Academic Press.MSC 1991 subject classification: 01A30, 01A60, 01A80, 03-03     

S.A.G.B.I. bases for rings of formal modular seminvariants

We use the theory of S.A.G.B.I. bases to construct a generating set for the ring of invariants for the four and five dimensional indecomposable modular representations of a cyclic group of prime order. We observe that for the four dimensional representation the ring of invariants is generated in degrees less than or equal to 2p–3, and for the five dimensional representation the ring of invariants is generated in degrees less than or equal to 2p–2. Received: January 22, 1997     

A class of three-replicate three-associate p.b.i.b. designs

Summary Partially balanced incomplete block (p.b.i.b.) designs of two and more associate classes have been constructed by Saha and Das [9] through the use of confounded designs for 2 ⁿ factorals. By dualising one series of two-associated p.b.i.b. designs given by them, a class of three-replicate three-associate p.b.i.b. designs have been obtained. This can be taken to be a new class of designs in the sense that they are not included by Nair [7] in his table of three-replicate three-associate p.b.i.b. designs.     

The kinship of E. H. Moore and R. L. Moore

Evidence is presented that E. H. Moore and R. L. Moore were seventh cousins.