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1.
P. C. Craighero R. Gattazzo M. C. Ronconi 《Annali di Matematica Pura ed Applicata》1981,129(1):81-130
Summary In this paper we classify the algebraic cubic surfaces of the affine space
is the complex field, whose algebraic curves are set-theoretic complete intersections of ; in other words surfaces such that every prime ideal of height 1in the coordinate ring [] of is the radical of a principal ideal; if is non singular in codimension 1this means that [] is semifactorial. We give the equations of such surfaces within linear isomorphisms of
providing also methods by which one can construct the equations of the surfaces cutting on its curves as set-theoretic complete intersections. Moreover for each of these surfaces we determine the minimum positive number such that every algebraic curve of with multiplicity of intersection , is complete intersection of itself with another surface
§ 8where the results are summarized). We tackle also the problem of such a classification over algebraically closed fields k different from .
Lavoro eseguito nell'ambito del G.N.S.A.G.A. del C.N.R. 相似文献
Lavoro eseguito nell'ambito del G.N.S.A.G.A. del C.N.R. 相似文献
2.
3.
Lu(t)+(u,F)g(t)=f(t), tS. , ( F, g). .
The authors wish to thank Professor Yu. A. Rozanov for his help and discussions. 相似文献
The authors wish to thank Professor Yu. A. Rozanov for his help and discussions. 相似文献
4.
Let m
, 0 m+ in Kato's class. We investigate the spectral function s( + m) where s( + m) denotes the upper bound of the spectrum of the Schrödinger operator + m. In particular, we determine its derivative at 0. If m- is sufficiently large, we show that there exists a unique 1 > 0 such that s( + 1m) = 0. Under suitable conditions on m+ it follows that 0 is an eigenvalue of + 1m with positive eigenfunction. 相似文献
5.
The number of subgroups of type and cotype in a finite abelian p-group of type is a polynomialg
with integral coefficients. We prove g
has nonnegative coefficients for all partitions and if and only if no two parts of differ by more than one. Necessity follows from a few simple facts about Hall-Littlewood symmetric functions; sufficiency relies on properties of certain order-preserving surjections that associate to each subgroup a vector dominated componentwise by . The nonzero components of (H) are the parts of , the type of H; if no two parts of differ by more than one, the nonzero components of – (H) are the parts of , the cotype of H. In fact, we provide an order-theoretic characterization of those isomorphism types of finite abelian p-groups all of whose Hall polynomials have nonnegative coefficients. 相似文献
6.
Let
be realhomogeneous functions in
ofdegree
and let bethe Borel measure on
given by
where dx denotes theLebesgue measure on
and > 0. Let T
be the convolution operator
and let
Assume that, for x 0, the followingtwo conditions hold:
vanishes only at h = 0 and
. In this paper we show that if
then E
is the empty set and if
then E
is the closed segment withendpoints
and
. Also, we give some examples. 相似文献
7.
A. B. Aleksandrov 《Journal of Mathematical Sciences》1993,63(2):115-129
Let be an inner function, let C, ¦¦=1. Then the harmonic function [(+)]/(–)] is the Poisson integral of a singular measure
D. N. Clark's known theorem enables us to identify in a natural manner the space H2 H2 with the space L2
(
).Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova Akademii Nauk SSSR, Vol. 170, pp. 7–33, 1989. 相似文献
8.
It is shown that the set [G,] of immersed linear networks in
that are parallel to a given immersed linear network
and have the same boundary as is a convex polyhedral subset of the configuration space of movable vertices of the graph G. The dimension of [G,] is calculated, and the number of its maximal faces is estimated. As an application, the spaces of all locally minimal and weighted minimal networks with fixed boundary and topology in
are described. Bibliography: 21 titles. 相似文献
9.
Let G be a finite permutation group on a set with no fixed points in and let m and k be integers with 0 < m < k. For a finite subset of the movement of is defined as move() = maxgG| g \ |. Suppose further that G is not a 2-group and that p is the least odd prime dividing |G| and move() m for all k-element subsets of . Then either || k + m or k (7m – 5) / 2, || (9m – 3)/2. Moreover when || > k + m, then move() m for every subset of . 相似文献
10.
D. M. Smirnov 《Algebra and Logic》2004,43(4):249-257
For integers 1 m < n, a Cantor variety with m basic n-ary operations i and n basic m-ary operations k is a variety of algebras defined by identities k(1(
), ... , m(
)) =
k and i(1(
), ... ,n(
)) = y
i, where
= (x
1., ... , x
n) and
= (y
1, ... , y
m). We prove that interpretability types of Cantor varieties form a distributive lattice, , which is dual to the direct product 1 × 2 of a lattice, 1, of positive integers respecting the natural linear ordering and a lattice, 2, of positive integers with divisibility. The lattice is an upper subsemilattice of the lattice
of all interpretability types of varieties of algebras. 相似文献
11.
Harold L. Putt 《Order》1984,1(2):173-185
In this note we discuss permutation groups (G, ) in which the set admits aG-invariant order. By aG-invariant partial order (G-partial order) we mean a partial order < of such that < implies g<g, for all and in andg inG. If the set admits aG-partial order which is a total order, then (G, ) is an O-permutation group (orderable permutation group).The main concern of this paper is the development of a foundation for partially ordered permutation groups analogous to the existing one for partially ordered groups, as found in Fuchs [2]. 相似文献
12.
Hossein Movasati 《Bulletin of the Brazilian Mathematical Society》2000,31(3):305-336
The main objective of this article is to study the topology of the fibers of a generic rational function of the type
in the projective space of dimension two. We will prove that the action of the monodromy group on a single Lefschetz vanishing cycle generates the first homology group of a generic fiber of
. In particular, we will prove that for any two Lefschetz vanishing cycles
0 and
1 in a regular compact fiber of
, there exists a mondromyh such thath(
0)=±
1.Partially supported by CNPq-Brazil. 相似文献
13.
Majorants and Extreme Points of Unit Balls in Bernstein Spaces 总被引:1,自引:1,他引:0
The Bernstein space B
p () (1
$$
" align="middle" border="0">
0) is the set of functions from L
p(
) having Fourier transforms (in the sense of generalized functions) with supports in the compact segment [- , ]. Every function f
has an analytic continuation onto the complex plane, which is an entire function of exponential type . The spaces B
p ()\, are conjugate Banach spaces. Therefore, the closed unit ball
in B
p () has a rich set of extreme (boundary) points:
coincides with the weakly * closed convex hull of its extreme points. Since, for 1< p< , B
p () is a uniformly convex space, only the balls
and
have nontrivially arranged sets of extreme points. In this paper, in terms of zeros of entire functions, we obtain necessary and sufficient conditions of extremeness for functions from
. 相似文献
14.
G. G. Gevorkyan 《Analysis Mathematica》1986,12(3):185-190
, (t) >0 E(–, +),E<, , ¦f(t)¦ (t)
xE, f(t)=0 (–, +). 相似文献
15.
W. Gähler 《Acta Mathematica Hungarica》2000,88(4):279-290
The paper deals with monadic as well as monadic-free topological notions. For defining these monadic-free notions the notion of basic triple is introduced. A lot of monadic-free topological notions are presented, for instance that of -convergence structure, -hull operator and -uniform structure. By means of a generalized metric, e.g. a probabilistic metric, and the general notion of -zero approach introduced in this paper, a -uniform structure is generated. In case of a fuzzy metric the related -uniform structure defines in a canonic way a fuzzy topology which is used for developing a fuzzy analysis and fuzzy calculus. 相似文献
16.
Noboru Hamada 《Designs, Codes and Cryptography》1997,10(1):41-56
Let k and d be any integers such that k 4 and
. Then there exist two integers and in {0,1,2} such that
. The purpose of this paper is to prove that (1) in the case k 5 and (,) = (0,1), there exists a ternary
code meeting the Griesmer bound if and only if
and (2) in the case k 4 and (,) = (0,2) or (1,1), there is no ternary
code meeting the Griesmer bound for any integers k and d and (3) in the case k 5 and
, there is no projective ternary
code for any integers k and such that 1k-3, where
and
for any integer i 0. In the special case k=6, it follows from (1) that there is no ternary linear code with parameters [233,6,154] , [234,6,155] or [237,6,157] which are new results. 相似文献
17.
(0; 0, 1) , {x
k
<x
k
*
<x
k+1}
k=1
n–1
{x
k
k=1
n
}., I, ,
n
(x)=P
n
(, )
(x)–n- , =, n3 . , x
0=+1 x
n+1= –1. II .
To the memory of Paul Erds
The research was supported by the Hungarian National Foundation for Scientific Research under Grant # T 914 244. 相似文献
To the memory of Paul Erds
The research was supported by the Hungarian National Foundation for Scientific Research under Grant # T 914 244. 相似文献
18.
J. Lippus 《Analysis Mathematica》1984,10(3):213-231
- ()N2,L
F
(
) — , 2- , {s
m()
f} -L.
— . (L
F(
),L
F(
) ={(k)} (kZ2) , fLF(
) f
,
, L
F(
). - ={()} ={()} , n(())m()n(()+())
. R() , ..
- . , . (L
F
(
),L
F
(
)) , R(,)=O(1) (x).
The author wishes to express his gratitude to S. A.Teljakovski for setting the problem and for his attention to this paper. 相似文献
The author wishes to express his gratitude to S. A.Teljakovski for setting the problem and for his attention to this paper. 相似文献
19.
In-Suk Wee 《Probability Theory and Related Fields》1990,85(4):469-488
Summary Let {X
t
} be a 1 process with stationary independent increments and its Lévy measurev be given byv{yy>x}=x
–L
1
(x), v{yy<–x}=x
–L
2
(x) whereL
1,L
2 are slowly varying at 0 and and 0<1. We construct two types of a nondecreasing functionh(t) depending on 0<<1 or =1 such that lim inf
a.s. ast 0 andt for some positive finite constantC.This research is partialy supported by a grant from Korea University 相似文献
20.
For a finite morphism f : X Y of smooth varieties such that f maps X birationally onto X=f(X), the local equations of f are obtained at the double points which are not triple. If C is the conductor of X over X, and
are the subschemes defined by C, then D and are shown to be complete intersections at these points, provided that C has the expected codimension. This leads one to determine the depth of local rings of X at these double points. On the other hand, when C is reduced in X, it is proved that X is weakly normal at these points, and some global results are given. For the case of affine spaces, the local equations of X at these points are computed. 相似文献