On p-adic L-functions attached to motives over ℚ II

We propose a definition of thep-adic L-function of a motiveM over ℚ assumingM admits at least one critical point, andp is ordinary forM. This corrects by a power of an earlier definition of B. Perrin-Riou and the author.     

On Serreʼs conjecture over imaginary quadratic fields

We study an analog of Serre?s conjecture over imaginary quadratic fields. In particular, we ask whether the weight recipe of Buzzard, Diamond and Jarvis will hold in this setting. Using a program written by the author, we provide computational evidence that this is in fact the case. In order to justify the method used in the program, we prove that a modular symbols method will work for arbitrary weights over imaginary quadratic fields.     

A remark on dynamical degrees of automorphisms of hyperkähler manifolds

We describe all the dynamical degrees of automorphisms of hyperkähler manifolds in terms of the first dynamical degree. We also present two explicit examples of different geometric flavours.     

On 𝒪ℒ∞ structures of nuclear C * -algebras

 We study the local operator space structure of nuclear C ^* -algebras. It is shown that a C ^* -algebra is nuclear if and only if it is an 𝒪ℒ_∞,λ space for some (and actually for every) λ>6. The 𝒪ℒ_∞ constant λ provides an interesting invariant

Groupoid and inverse semigroup presentations of ultragraph C *-algebras

Inspired by the work of Paterson on C ^* -algebras of directed graphs, we show how to associate a groupoid to an ultragraph in such a way that the C ^*-algebra of is canonically isomorphic to Tomforde’s C ^*-algebra . The groupoid is built from an inverse semigroup naturally associated to . A.E. Marrero was supported by grants from the National Science Foundation and the Sloan Foundation and by a GAANN Fellowship. Many of the results here are taken from this author’s dissertation [7]. P.S. Muhly was supported by a grant from the National Science Foundation (DMS-0355443).     

On spline approximation of sliced inverse regression

The dimension reduction is helpful and often necessary in exploring the nonparametric regression structure.In this area,Sliced inverse regression (SIR) is a promising tool to estimate the central dimension reduction (CDR) space.To estimate the kernel matrix of the SIR,we herein suggest the spline approximation using the least squares regression.The heteroscedasticity can be incorporated well by introducing an appropriate weight function.The root-n asymptotic normality can be achieved for a wide range choice of knots.This is essentially analogous to the kernel estimation.Moreover, we also propose a modified Bayes information criterion (BIC) based on the eigenvalues of the SIR matrix.This modified BIC can be applied to any form of the SIR and other related methods.The methodology and some of the practical issues are illustrated through the horse mussel data.Empirical studies evidence the performance of our proposed spline approximation by comparison of the existing estimators.     

Diophantine definability over non-finitely generated non-degenerate modules of algebraic extensions of ℚ

We investigate the issues of Diophantine definability over the non-finitely generated version of non-degenerate modules contained in the infinite algebraic extensions of the rational numbers. In particular, we show the following. Let k be a number field and let K _inf be a normal algebraic, possibly infinite, extension of k such that k has a normal extension L linearly disjoint from K _inf over k. Assume L is totally real and K _inf is totally complex. Let M _inf be a non-degenerate O _k -module, possibly non-finitely generated and contained in O _Kinf . Then M _inf contains a submodule Mˉ _inf such that M _inf /Mˉ _inf is torsion and O _k has a Diophantine definition over Mˉ _inf . Received: 4 May 1999 / Published online: 21 March 2001     

On σ-algebras related to the measurability of compositions

Given a measurable space (T, F), a set X, and a map ?: T → X, the σ-algebras N _Ф = ?_?∈Φ N _?, and M _Φ = ?_?∈Φ N _?, where G _?(t) = (t, ?(t)) and Φ ? X ^T , are considered. These σ-algebras are used to characterize the (F, B, ?)-measurability of the compositions g ○ ? and f о G _?, where g: X → Y, f: T × X → Y, and (Y, ?) is a measurable space. Their elements are described without using the operations ? ^?1 and G _? ^?1 .     

On the degree of iterates of automorphisms¶of the affine plane

For a polynomial automorphism f of ?² _ℂ, we set τ = deg f ²)/(deg f). We prove that τ≤ 1 if and only if f is triangularizable. In this situation, we show (by using a deep result from number theory known as the theorem of Skolem–Mahler–Lech) that the sequence (deg f ⁿ ) _{n ∈ℕ} is periodic for large n. In the opposite case, we prove that τ is an integer (τ≥ 2) and that the sequence (deg f ⁿ ) _{n ∈ℕ} is a geometric progression of ratio τ. In particular, if f is any automorphism, we obtain the rationality of the formal series . Received: 1 December 1997     

On Knebusch’s Norm Principle for quadratic forms over semi-local rings

We prove Knebusch’s Norm Principle for finite extensions of semi-local regular rings containing a field of characteristic 0. As an application we prove the Grothendieck-Serre conjecture on principal homogeneous spaces for the case of spinor groups of regular quadratic forms over a field of characteristic 0.     

On the automorphisms of some line congruences in ℙ3

The automorphisms of line congruences in ³ are studied via the analysis of the automorphisms of the associated focal loci. This study is applied to a Veronese surface (i.e. to a congruence of chords of a twisted cubic) and to the rational scrolls in the Grassmannian G(1, 3).     

Class numbers of cyclic 2-extensions and Gross conjecture over ℚ

The Gross conjecture over ? was first claimed by Aoki in 1991. However, the original proof contains too many mistakes and false claims to be considered as a serious proof. This paper is an attempt to find a sound proof of the Gross conjecture under the outline of Aoki. We reduce the conjecture to an elementary conjecture concerning the class numbers of cyclic 2-extensions of ?.     

On the divisibility of the class number of the imaginary quadratic field ℚ (\sqrt {a^2 - 4k^n } )

LetD be a positive integer which is square free, and leth (–D) denote the class number of the imaginary quadratic field 2e (–D). In this paper we prove that ifD' exp exp exp 1000,D=4k –a ², wherea, k andn are integers witha>0,k>1,n>1, then

On the Constructions of the Non-Abelian p 3-Extensions Over ℚ

Let p be an odd prime, and let G be one of the two non-abelian groups of order p ³. Ledet [3 Ledet , A. ( 2000 ). Generic and explicit realization of small p-groups . Journal of Symbolic Computation 30 : 859 – 865 . [Google Scholar]] described explicit G-extensions over the rationales in special cases. In this article, we generalize his results and show how non-tame G-extensions can be constructed having exactly two ramified primes.     

On the Characterization of a Class of π—inverse Semigroups

51.PreliminatriesS.Bogdanovicgaveacharacterizationforstronglyrr-inversesemigroupsinLlJ.TheclassofrightinversesemigroupsisinvestigatedbyP.S-Venkatesanin[2j.Inthispaper,thenotionofstronglyrightff-inversesemigroupsisintroduced.Characteri-zationofthisclassofsemigroupsobtained-Definition1.1[1jAff-regularsemigroupsissaidtobeK-orthodoxifE,,thesetofidem-potentsinS,isasubsemigroupofS.Definition1.2[1jAK-regularsemigroupsiscalledstronglyK-inverseifef=feforev-erye,feE,.Definition1.3Aff-regularsemi…     

On the use of simplex methods in constructing quadratic models

In this paper,we investigate the quadratic approximation methods.After studying the basic idea of simplex methods,we construct several new search directions by combining the local information progressively obtained during the iterates of the algorithm to form new subspaces.And the quadratic model is solved in the new subspaces.The motivation is to use the information disclosed by the former steps to construct more promising directions.For most tested problems,the number of function evaluations have been reduced obviously through our algorithms.     

Normalizer of a group of “diagonal” automorphisms in algebras over a commutative ring

Let S be a faithful algebra over commutative ring R. It is assumed that S is additively generated by its invertible elements. It is shown that the nomalizer of subgroup Aut(S_s) of group Aut(S_R) coincides with the semidirect product Aut(S_S) Aut(S/R),where the second factor is the group of all ring automorphisms of ring S identical on R.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova Akademiya Nauk SSSR, Vol. 191, pp. 5–8, 1991.