共查询到20条相似文献,搜索用时 906 毫秒
1.
Moshe Sniedovich 《Mathematical Programming》1989,43(1-3):329-347
We propose a solution strategy for fractional programming problems of the form max
xx
g(x)/ (u(x)), where the function satisfies certain convexity conditions. It is shown that subject to these conditions optimal solutions to this problem can be obtained from the solution of the problem max
xx
g(x) + u(x), where is an exogenous parameter. The proposed strategy combines fractional programming andc-programming techniques. A maximal mean-standard deviation ratio problem is solved to illustrate the strategy in action. 相似文献
2.
R
n. , , , F R
n, F , R
n R
n .
p,q
(Rn), >0, 1, q, — ( ) Rn. ,
p,q
(Rn) F Rn. , q B
p,q
(F), = – (n–)/, >0, — « », ad — F, . , . : , F=R
d,F— « » F— R
n, « », F. .
This work has been supported in part by the Swedish Natural Science Research Council. 相似文献
This work has been supported in part by the Swedish Natural Science Research Council. 相似文献
3.
P. Révész 《Probability Theory and Related Fields》1992,93(1):21-37
Summary We say that the discD()R
2, of radius , located around the origin isp-covered in timeT by a Wiener processW(·) if for anyzD() there exists a 0tT such thatW(t) is a point of the disc of radiusp, located aroundz. The supremum of those 's (0) is studied for which,D() isp-covered inT. 相似文献
4.
Donald I. Cartwright Anna Maria Mantero Tim Steger Anna Zappa 《Geometriae Dedicata》1993,47(2):167-223
If (P, L) is a projective plane and is a triangle presentation compatible with a point-line correspondence :P L, then gives rise to a group and a thick building of typeÃ
2 on the vertices of which acts simply transitively. We find all triangle presentations (up to natural equivalence) compatible with some point-line correspondence :P L, when (P, L) is the projective plane of orderq=2 orq=3. For some, but not all, of these , is isomorphic to the building associated withG=PGL(3,K) whereK is a local field with discrete valuation and residual field of orderq. We identify the for which this is the case, and in these cases, find embeddings of intoG. We also describe the arithmetic nature of these groups. 相似文献
5.
LetX, Y be finite sets and suppose thatF is a collection of pairs of sets (F, G),FX,GY satisfying |FF|s, |GG|t and |FF|+|GG|s+t+1 for all (F, G),F, GF. Extending a result of Sali, we determine the maximum ofF. 相似文献
6.
A variety of Galerkin methods are studied for the parabolic equationu
t
=(a(x)
u),x
n
,t (O,T], subject to the nonlinear boundary conditionu
v
=g(x,t,u),x,t (O,T] and the usual initial condition. Optimal order error estimates are derived both inL
2 () andH
1 () norms for all methods treated, including several that produce linear computational procedures.The authors were partially supported by The National Science Foundation during the preparation of this paper. 相似文献
7.
A. G. Pinus 《Mathematical Notes》1972,11(1):54-57
It is shown that if a linearly ordered set B does not contain as subsets sets of order type
and
*
then B can be embedded in 2
. We construct an example of a set satisfying the above conditions which cannot be embedded in any 2
if <
. Simultaneously we show that for any ordinal, 2
+1
cannot be embedded in 2
and that there exists at least
+1
distinct dense order types of cardinality 2
.Translated from Matematicheskie Zametki, Vol. 11, No. 1, pp. 83–88, January, 1972.In conclusion, I wish to take the opportunity to thank Yu. L. Ershov for kindness and assistance in this work. 相似文献
8.
Summary We study integral functionals of the formF(u, )=
f(u)dx, defined foru C1(;R
k), R
n
. The functionf is assumed to be polyconvex and to satisfy the inequalityf(A) c0¦(A)¦ for a suitable constant c0 > 0, where (A) is then-vector whose components are the determinants of all minors of thek×n matrixA. We prove thatF is lower semicontinuous onC
1(;R
k) with respect to the strong topology ofL
1(;R
k). Then we consider the relaxed functional , defined as the greatest lower semicontinuous functional onL
1(;R
k
) which is less than or equal toF on C1(;R
k). For everyu BV(;R
k) we prove that (u,)
f(u)dx+c0¦Dsu¦(), whereDu=u dx+Dsu is the Lebesgue decomposition of the Radon measureDu. Moreover, under suitable growth conditions onf, we show that (u,)=
f(u)dx for everyu W1,p(;R
k), withp min{n,k}. We prove also that the functional (u, ) can not be represented by an inte- gral for an arbitrary functionu BVloc(R
n;R
k). In fact, two examples show that, in general, the set function (u, ) is not subadditive whenu BVloc(R
n;R
k), even ifu W
loc
1,p
(R
n;R
k) for everyp < min{n,k}. Finally, we examine in detail the properties of the functionsu BV(;R
k) such that (u, )=
f(u)dx, particularly in the model casef(A)=¦(A)¦. 相似文献
9.
We define (n) to be the largest number such that for every setP ofn points in the plane, there exist two pointsx, y P, where every circle containingx andy contains (n) points ofP. We establish lower and upper bounds for (n) and show that [n/27]+2(n)[n/4]+1. We define
for the special case where then points are restricted to be the vertices of a convex polygon. We show that
. 相似文献
10.
[4] , . 相似文献
11.
Summary In this paper we study the noncharacteristic Cauchy problem, ut–(a(x)ux)x=0, x(0, l), t.(0, T], u(0, t)=(t), ux(0,t)=0, 0tT, assuming only L for a. In the case of weak a priori bounds on u, we derive stability estimates on u of Hölder type in the interior and of logarithmic type at the boundary. Also the continuous dependence on a is considered.
Sunto Nel presente lavoro consideriamo il problema di Cauchy non ben posto ut= (a(x)ux)x, x(0, l), t(0, T), u(0, t)=(t), ux(0, t)=0, 0tT. Supponiamo che a sia misurabile e limitato inferiormente e superiormente da constanti positive. Introduciamo delle limitazioni a priori su u e dimostriamo la dipendenza continua di u rispetto al dato sia in (0, l)×(0, T) (di tipo hölderiano) sia per x=l (di tipo logaritmico). Consideriamo, inoltre, la dipendenza continua di u da a.相似文献
12.
Stuart A. Steinberg 《Czechoslovak Mathematical Journal》2001,51(2):387-394
In an -group M with an appropriate operator set it is shown that the -value set (M) can be embedded in the value set (M). This embedding is an isomorphism if and only if each convex -subgroup is an -subgroup. If (M) has a.c.c. and M is either representable or finitely valued, then the two value sets are identical. More generally, these results hold for two related operator sets 1 and 2 and the corresponding -value sets
and
. If R is a unital -ring, then each unital -module over R is an f-module and has
exactly when R is an f-ring in which 1 is a strong order unit. 相似文献
13.
, (n), - (P
n
), P
n
(A
n
)>0P
n
(A
n
)0,n. [15] - , . , P
n
P
n
T
n
T
n
. 相似文献
14.
V. A. Andrienko 《Analysis Mathematica》1996,22(4):243-266
( ) . .
Dedicated to Professor K. Tandori on his seventieth birthday
This research was supported in part by Grant # K41 100 of the Joint Fund of the Government of Ukraine and the International Science Foundation. 相似文献
Dedicated to Professor K. Tandori on his seventieth birthday
This research was supported in part by Grant # K41 100 of the Joint Fund of the Government of Ukraine and the International Science Foundation. 相似文献
15.
This paper investigates some kinds of roughly convex functions, namely functions having one of the following properties: -convexity (in the sense of Klötzler and Hartwig), -convexity and midpoint -convexity (in the sense of Hu, Klee, and Larman), -convexity and midpoint -convexity (in the sense of Phu). Some weaker but equivalent conditions for these kinds of roughly convex functions are stated. In particular, piecewise constant functions
satisfying f(x) = f([x]) are considered, where [x] denotes the integer part of the real number x. These functions appear in numerical calculation, when an original function g is replaced by f(x):=g([x]) because of discretization. In the present paper, we answer the question of when and in what sense such a function f is roughly convex. 相似文献
16.
N. M. Ivochkina 《Journal of Mathematical Sciences》1984,26(6):2349-2359
One proves that a priori boundedness of the norm
of the solution of the problem det(Uxx)=f(x,u,ux)>>0,u¦=0. The magnitudes of the exponents,() depends on whether the arguments u p occur or not in f (x,u,p).Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 125, pp. 74–90, 1983. 相似文献
17.
Héctor H. Cuenya 《Analysis Mathematica》2000,26(3):175-186
Let (, A, ) be a measure space, a function seminorm on M, the space of measurable functions on , and M
the space {f M : (f) < }. Every Borel measurable function : [0, ) [0, ) induces a function : M M by (f)(x) = (|f(x)|). We introduce the concepts of -factor and -invariant space. If is a -subadditive seminorm function, we give, under suitable conditions over , necessary and sufficient conditions in order that M
be invariant and prove the existence of -factors for . We also give a characterization of the best -factor for a -subadditive function seminorm when is -finite. All these results generalize those about multiplicativity factors for function seminorms proved earlier. 相似文献
18.
Norbert?Hegyvri 《Acta Mathematica Hungarica》2005,106(3):187-195
19.
Zoran Vondraček 《Journal of Theoretical Probability》1991,4(2):457-464
Let (Y
t, Qx) be a strong Markov process in a bounded Lipschitz domainD with continuous paths up to its lifetime , and let (X
t, Px) be a Brownian motion inD. IfY
– exists in D andQ
x(Y– C)=Px(X– C) for all Borel subsetsC of D and allx, thenY is a time change ofX. 相似文献
20.
Let (x) stand for the number of primes not exceedingx. In the present work it is shown that if 23/421,yx
andx>x() then (x)–(x–y)>y/(100 logx). This implies for the difference between consecutive primes the inequalityp
n+1–p
n
p
n
23/42
. 相似文献