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1.
《Quaestiones Mathematicae》2013,36(1-4):55-67
ABSTRACT The nil radical, N(M) of a Γ-ring M was defined by Coppage and Luh [3], and shown by Groenewald [4] to be a special radical. We define s-prime ideals of M and show that N(M) is equal to the intersection of the s-prime ideals of M. If R is a ring, the nil radical of R considered as a Γ-ring with Γ = R is equal to the upper nil radical of R. We also give a sufficient condition for the equality N(R)* = N(M), where R is the right operator ring of M, and N(R) is its upper nil radical. 相似文献
2.
《Quaestiones Mathematicae》2013,36(1):7-15
ABSTRACT In this note, we define the antisimple radical, A(M), of a Γ-ring M. A(M) is shown to be a special radical, and two characterizations of antisimple rings due to Szész are extended to Γ-rings. If R is the right operator ring of M, then A(R)* = A(M), where A(R) is the antisimple radical of R. If m,n are positive integers, then A(Mmn) = (A(M))mn, where Mmn denotes the group m x n matrices over M, considered as a Γnm -ring with the operations of matrix addition and multiplication. 相似文献
3.
M. B. Sevryuk 《Journal of Mathematical Sciences》1992,60(5):1663-1680
Let R be a fixed linear involution (R
2=id) of the spaceR
n
. A linear operator M is said to bereversible with respect to R if RM R=M–1 and infinitesimally reversible with respect to R if M R=–RM. A linear differential equation dx/dt=B(t)x is said to be reversible with respect to R if V(t)R –RV(–t). We construct normal forms and versal deformations for reversible and infinitesimally reversible operators. The results are applied to describe the homotopy classes of strongly stable reversible linear differential equations with periodic coefficients. The analogous theory for linear Hamiltonian systems was developed by J. Williamson, M. G. Krein, I.M. Gel'fand, V. B. Lidskii, D. M. Galin, and H. Koçak.Translated fromTrudy Seminara imeni I. G. Petrovskogo, No. 15, pp. 33–54, 1991. Original article submitted April 27, 1988. 相似文献
4.
《Quaestiones Mathematicae》2013,36(1):33-48
Abstract For an arbitrary left R-module M, we denote by F(M) the class of left R-modules F such that for any exact sequence 0 → A α→ B of left R-modules and any R-homomorphism β: A → M factoring through F, there exists an R- homomorphism γ: B → M such that β = γα. For any given class R of left R-modules, we denote ∩E?R F(M) by F(R) or simply by 9 if the context is clear. The class of short exact sequences E of left R-modules relative to which each ME'JR has the injective property, is denoted by E(R) or just &. Relative properties of RR, F and E are investigated for a given class R. The special case where JR is the class of all pure-injective left R-modules is explored. In this way the class F of coflat left R-modules is introduced and it is pointed out that a module is coflat if and only if it is absolutely pure. 相似文献
5.
A.R. Darwich 《Stochastics An International Journal of Probability and Stochastic Processes》2013,85(1-2):393-409
We study the asymptotic behaviour of the process d M ¢ m 1 M , where M is an R n -continuous vector local martingale and d M ¢ m 1 is the inverse of its predictable quadratic variation (a matrix-valued process). We also give an application (strong consistency and rate of convergence) to multiple linear regression. 相似文献
6.
Michal Botur 《Mathematica Slovaca》2010,60(2):171-178
Many algebras arising in logic have a lattice structure with intervals being equipped with antitone involutions. It has been
proved in [CHK1] that these lattices are in a one-to-one correspondence with so-called basic algebras. In the recent papers
[BOTUR, M.—HALAŠ, R.: Finite commutative basic algebras are MV-algebras, J. Mult.-Valued Logic Soft Comput. (To appear)]. and [BOTUR, M.—HALAŠ, R.: Complete commutative basic algebras, Order 24 (2007), 89–105] we have proved that every finite commutative basic algebra is an MV-algebra, and that every complete commutative
basic algebra is a subdirect product of chains. The paper solves in negative the open question posed in [BOTUR, M.—HALAŠ,
R.: Complete commutative basic algebras, Order 24 (2007), 89–105] whether every commutative basic algebra on the interval [0, 1] of the reals has to be an MV-algebra. 相似文献
7.
Abstract The New Bookstore in Town—Books Found on the Shelf Reasoning with Statistics, Third ed. by Frederick Williams. New York: Holt, Reinhart and Winston, 1986, 224 pp., $16.95, paperback (ISBN 0-03-019536-5). Reviewed by Michael M. Meyer Envisioning Information by Edward R. Tufte, Cheshire, Connecticut: Graphics Press, 1990, 126 pp., $48., hardcover (ISBN 0-961-3921-1-8). Reviewed by William F. Eddy 相似文献
8.
In 1998, Kleinbock and Margulis proved Sprindzuk’s conjecture pertaining to metrical Diophantine approximation (and indeed
the stronger Baker–Sprindzuk conjecture). In essence, the conjecture stated that the simultaneous homogeneous Diophantine
exponent w
0(x) = 1/n for almost every point x on a nondegenerate submanifold M \mathcal{M} of
\mathbbRn {\mathbb{R}^n} . In this paper, the simultaneous inhomogeneous analogue of Sprindzuk’s conjecture is established. More precisely, for any
“inhomogeneous” vector θ ∈
\mathbbRn {\mathbb{R}^n} we prove that the simultaneous inhomogeneous Diophantine exponent w
0(x
,
θ) is 1/n for almost every point x on M \mathcal{M} . The key result is an inhomogeneous transference principle which enables us to deduce that the homogeneous exponent w
0(x) is 1/n for almost all x ∈ M \mathcal{M} if and only if, for any θ ∈
\mathbbRn {\mathbb{R}^n} , the inhomogeneous exponent w
0(x
,
θ) = 1/n for almost all x ∈ M \mathcal{M} . The inhomogeneous transference principle introduced in this paper is an extremely simplified version of that recently discovered
by us. Nevertheless, it should be emphasised that the simplified version has the great advantage of bringing to the forefront
the main ideas while omitting the abstract and technical notions that come with describing the inhomogeneous transference
principle in all its glory. 相似文献
9.
ABSTRACT M. Masuda recently provided the missing piece proving a conjecture of R.P. Stanley on the characterization of f-vectors for Gorenstein? simplicial posets. We propose a slight simplification of Masuda's proof. 相似文献
10.
《Optimization》2012,61(1):39-50
We extend the convergence analysis of a smoothing method [M. Fukushima and J.-S. Pang (2000). Convergence of a smoothing continuation method for mathematical programs with complementarity constraints. In: M. Théra and R. Tichatschke (Eds.), Ill-posed Variational Problems and Regularization Techniques, pp. 99–110. Springer, Berlin/Heidelberg.] to a general class of smoothing functions and show that a weak second-order necessary optimality condition holds at the limit point of a sequence of stationary points found by the smoothing method. We also show that convergence and stability results in [S. Scholtes (2001). Convergence properties of a regularization scheme for mathematical programs with complementarity constraints. SIAM J. Optim., 11, 918–936.] hold for a relaxation problem suggested by Scholtes [S. Scholtes (2003). Private communications.] using a class of smoothing functions. In addition, the relationship between two technical, yet critical, concepts in [M. Fukushima and J.-S. Pang (2000). Convergence of a smoothing continuation method for mathematical programs with complementarity constraints. In: M. Théra and R. Tichatschke (Eds.), Ill-posed Variational Problems and Regularization Techniques, pp. 99–110. Springer, Berlin/Heidelberg; S. Scholtes (2001). Convergence properties of a regularization scheme for mathematical programs with complementarity constraints. SIAM J. Optim., 11, 918–936.] for the convergence analysis of the smoothing and regularization methods is discussed and a counter-example is provided to show that the stability result in [S. Scholtes (2001). Convergence properties of a regularization scheme for mathematical programs with complementarity constraints. SIAM J. Optim., 11, 918–936.] cannot be extended to a weaker regularization. 相似文献
11.
The geometry of slant submanifolds of a nearly trans-Sasakian manifold is studied when the tensor field Q is parallel. It is proved that Q is not parallel on the submanifold unless it is anti-invariant and thus the result of [CABRERIZO, J. L.—CARRIAZO, A.—FERNANDEZ,
L. M.—FERNANDEZ, M.: Slant submanifolds in Sasakian manifolds, Glasg. Math. J. 42 (2000), 125–138] and [GUPTA, R. S.—KHURSHEED HAIDER, S. M.—SHARFUDIN, A.: Slant submanifolds of a trans-Sasakian manifold, Bull. Math. Soc. Sci. Math. Roumanie (N.S.) 47 (2004), 45–57] are generalized. 相似文献
12.
Paola Biondi 《Rendiconti del Circolo Matematico di Palermo》1998,47(2):265-276
LetS be a finite planar space such that any two distinct planes intersect in a line. We show thatk≤n
2+1 for anyk-cap ofS, wheren is the order ofS. Moreover, if a (n
2+1)-cap exists inS, a necessary and sufficient condition is provided forS to be embeddable in a 3-dimensional projective space.
Work supported by the National Research Project “Strutture geometriche, Combinatoria e loro applicazioni” of the italian M.U.R.S.T. 相似文献
13.
Prof. Dr Vlastimil Pták DrSc 《manuscripta mathematica》1988,62(2):131-144
In this paper we deal with singularities of the linear systems of plane curves passing through S, where S is a zerodimensional closed subscheme of degree n of
P
2=P
k
2
,k an algebraically closed field of any characteristic. We determine the least degree of a nonsingular curve passing through S, when S is in uniform position.
This paper was written while the author was member of C.N.R., Sez. 3 of G.N.S.A.G.A. and was supported by M.P.I. funds 相似文献
14.
《复变函数与椭圆型方程》2012,57(2):149-154
Let G be the algebraic limit of a sequence $ \{ G_m\} $ of r generator subgroups of $ M(\bar {R}^n) $ . We prove that (i) if $ G_m $ is elementary, then G is elementary; (ii) if $ G_m $ is not non-elementary and non-discrete and G satisfies the Condition A, then G is not non-elementary and non-discrete. Let $ E_l = \{ (f_1, f_2,\ldots ,f_l): f_1,f_2,\ldots ,f_l\in M(\bar {R}^2), \langle \,f_1,f_2,\ldots , \,f_l \rangle\ elementary\} $ and $ D_l = \{ (f_1,f_2,\ldots ,f_l): f_1,f_2,\ldots ,f_l\in M(\bar {R}^2), \langle \,f_1,f_2,\ldots ,f_l \rangle\ discrete\} $ . we obtain that the set $ E_l , D_l\cup E_l $ and $ D_l\cap E_l^c $ are closed in $ \underbrace {M(\bar {R}^2)\times \cdots \times M(\bar {R}^2)}\limits _{l} $ . 相似文献
15.
Özgür Ceyhan 《Selecta Mathematica, New Series》2007,13(2):203-237
The moduli space parameterizes the isomorphism classes of S-pointed stable real curves of genus zero which are invariant under relabeling by the involution σ. This moduli space is stratified according to the degeneration types of σ-invariant curves. The degeneration types of σ-invariant curves are encoded by their dual trees with additional decorations. We construct a combinatorial graph complex
generated by the fundamental classes of strata of . We show that the homology of is isomorphic to the homology of our graph complex. We also give a presentation of the fundamental group of .
相似文献
16.
Jiří Močkoř 《Czechoslovak Mathematical Journal》2007,57(2):631-645
Two categories Set(Ω) and SetF(Ω) of fuzzy sets over an MV-algebra Ω are investigated. Full subcategories of these categories are introduced consisting of objects (sub(A, δ), σ), where
sub(A, δ) is a subset of all extensional subobjects of an object (A, δ). It is proved that all these subcategories are quasi-reflective subcategories in the corresponding categories.
Supported by MSM6198898701, grant GAČR 201/04/0381/2 and grant 1M0572. 相似文献
17.
S. I. Maksymenko 《Ukrainian Mathematical Journal》2010,62(7):1109-1125
Let
F:M ×\mathbbR ? M {\mathbf{F}}:M \times \mathbb{R} \to M be a continuous flow on a manifold M, let V ⊂ M be an open subset, and let
x:V ? \mathbbR \xi :V \to \mathbb{R} be a continuous function. We say that ξ is a period function if F(x, ξ(x)) = x for all x ∈ V. Recently, for any open connected subset V ⊂ M; the author has described the structure of the set P(V) of all period functions on V. Assume that F is topologically conjugate to some C1 {\mathcal{C}^1} -flow. It is shown in this paper that, in this case, the period functions of F satisfy some additional conditions that, generally speaking, are not satisfied for general continuous flows. 相似文献
18.
§1IntroductionLetGbeaconnectedgraphwithvertex-setV(G)andedge-setE(G).Denotebye=(x,y)theedgejoiningtheverticesxandyofG.Am-cliq... 相似文献
19.
Summary
The existence of 2 -dimensional invariant tori and their bifurcation in 3-dimensional invariant tori are investigated for a family of (non- hamiltonian) differential sistems in
R
4.Techniques inspired to the « K.A.M. theory » are used to identify « paths of bifurcation » in the parameters space.Work performed under the auspices of the Italian Council of Research (C.N.R.) and of Ministero della Pubblica Istruzione (M.P.I.). 相似文献
20.
R. A. R. Monzo 《Semigroup Forum》1973,6(1):59-68
This investigation was stimulated by a question raised by F.R. McMorris and M. Satyanarayana [Proc. Amer. Math. Soc.
33 (1972), 271–277] which asked whether a regular semigroup with a tree of idempotents is categorical. The question is answered
in the affirmative. Characterizations of categorical semigroups are found within the following classes of semigroups: regular
semigroups, bands, commutative regular semigroups, unions of simple semigroups, semilattices of groups, and commutative semigroups.
Some results are related to part of the work of M. Petrich [Trans. Amer. Math. Soc.
170 (1972), 245–268]. For instance, it is shown that the poset of J-classes of any regular categorical semigroup is a tree; however,
an example of a regular non-categorical semigroup is given in which the poset of J-classes is a chain.
It is also shown that the condition that the subsemigroup of idempotents be categorical is sufficient, but not necessary,
for an orthodox semigroup to be categorical. 相似文献