共查询到20条相似文献,搜索用时 187 毫秒
1.
Vladimir Petrov Kostov 《Bulletin des Sciences Mathématiques》2007,131(5):477
A real polynomial P of degree n in one real variable is hyperbolic if its roots are all real. A real-valued function P is called a hyperbolic polynomial-like function (HPLF) of degree n if it has n real zeros and P(n) vanishes nowhere. Denote by the roots of P(i), k=1,…,n−i, i=0,…,n−1. Then in the absence of any equality of the form one has ∀i<j, (the Rolle theorem). For n?4 (resp. for n?5) not all arrangements without equalities (∗) of n(n+1)/2 real numbers and compatible with (∗∗) (we call them admissible) are realizable by the roots of hyperbolic polynomials (resp. of HPLFs) of degree n and of their derivatives. For n=5 we show that from 286 admissible arrangements, exactly 236 are realizable by HPLFs; from these 236 arrangements, 116 are realizable by hyperbolic polynomials and 24 by perturbations of such. 相似文献
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Marco Franciosi 《Advances in Mathematics》2004,186(2):317-333
Let C be a numerically connected curve lying on a smooth algebraic surface. We show that if is an ample invertible sheaf satisfying some technical numerical hypotheses then is normally generated. As a corollary we show that the sheaf ωC⊗2 on a numerically connected curve C of arithmetic genus pa?3 is normally generated if ωC is ample and does not exist a subcurve B⊂C such that pa(B)=1=B(C−B). 相似文献
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Ming-Yi Lee 《Journal of Mathematical Analysis and Applications》2006,324(2):1274-1281
Let w be a Muckenhoupt weight and be the weighted Hardy spaces. We use the atomic decomposition of and their molecular characters to show that the Bochner-Riesz means are bounded on for 0<p?1 and δ>max{n/p−(n+1)/2,[n/p]rw−1(rw−1)−(n+1)/2}, where rw is the critical index of w for the reverse Hölder condition. We also prove the boundedness of the maximal Bochner-Riesz means for 0<p?1 and δ>n/p−(n+1)/2. 相似文献
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Yuan Zhou 《Journal of Mathematical Analysis and Applications》2011,382(2):577-593
The author establishes some geometric criteria for a Haj?asz-Sobolev -extension (resp. -imbedding) domain of Rn with n?2, s∈(0,1] and p∈[n/s,∞] (resp. p∈(n/s,∞]). In particular, the author proves that a bounded finitely connected planar domain Ω is a weak α-cigar domain with α∈(0,1) if and only if for some/all s∈[α,1) and p=(2−α)/(s−α), where denotes the restriction of the Triebel-Lizorkin space on Ω. 相似文献
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A higher-dimensional partial Legendre transform, and regularity of degenerate Monge-Ampère equations
Cristian Rios 《Advances in Mathematics》2005,193(2):373-415
In dimension n?3, we define a generalization of the classical two-dimensional partial Legendre transform, that reduces interior regularity of the generalized Monge-Ampère equation to regularity of a divergence form quasilinear system of special form. This is then used to obtain smoothness of C2,1 solutions, having n-1 nonvanishing principal curvatures, to certain subelliptic Monge-Ampère equations in dimension n?3. A corollary is that if k?0 vanishes only at nondegenerate critical points, then a C2,1 convex solution u is smooth if and only if the symmetric function of degree n-1 of the principal curvatures of u is positive, and moreover, u fails to be when not smooth. 相似文献
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In an earlier paper the authors showed that with one exception the nonorientable genus of the graph with m≥n−1, the join of a complete graph with a large edgeless graph, is the same as the nonorientable genus of the spanning subgraph . The orientable genus problem for with m≥n−1 seems to be more difficult, but in this paper we find the orientable genus of some of these graphs. In particular, we determine the genus of when n is even and m≥n, the genus of when n=2p+2 for p≥3 and m≥n−1, and the genus of when n=2p+1 for p≥3 and m≥n+1. In all of these cases the genus is the same as the genus of Km,n, namely ⌈(m−2)(n−2)/4⌉. 相似文献
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Wolfgang Reichel 《Journal of Mathematical Analysis and Applications》2003,287(1):75-89
We continue Part I of this paper on polyharmonic boundary value problems (−Δ)mu=f(u) on , , with Dirichlet boundary conditions. Here Ω is a bounded or unbounded conformally contractible domain as defined in Part I. The uniqueness principle proved in Part I is applied to show the following theorems: if f(s)=λs+|s|p−1s, λ?0, with a supercritical p>(n+2m)/(n−2m) we extend the well-known non-existence result of Pucci and Serrin (Indiana Univ. Math. J. 35 (1986) 681-703) for bounded star-shaped domains to the wider class of bounded conformally contractible domains. We give two examples of domains in this class which are not star-shaped. In the case where 1<p<(n+2m)/(n−2m) is subcritical we give lower bounds for the L∞-norm of non-trivial solutions. For certain unbounded conformally contractible domains, 1<p<(n+2m)/(n−2m) subcritical and λ?0 we show that the only smooth solution in H2m−1(Ω) is u≡0. Finally, on a bounded conformally contractible domain uniqueness of non-trivial solutions for f(s)=λ(1+|s|p−1s), p>(n+2m)/(n−2m), supercritical and small λ>0 is proved. Solutions are critical points of a functional on a suitable space X. The theorems are proved by finding one-parameter groups of transformations on X which strictly reduce the values of . Then the uniqueness principle of Part I can be applied. 相似文献
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Yuri Agranovich 《Journal of Mathematical Analysis and Applications》2005,306(1):1-17
Given two monic polynomials P2n and P2n−2 of degree 2n and 2n−2 (n?2) with complex coefficients and with disjoint zero sets. We give necessary and sufficient conditions on these polynomials such that there exist two n×n Jacobi matrices B and C for which
11.
Robert D. Little 《Journal of Pure and Applied Algebra》2007,208(3):805-819
Let g:M2n?M2n be an orientation preserving PL map of period m>2. Suppose that the cyclic action defined by g is locally linear PL, fixing a locally flat submanifold F with components only of dimension 0 or 2n−2, and regular. Let ?(m) be Euler’s number and ρ(m)=?(m)−1 if m is a power of 2 and ρ(m)=?(m) otherwise. If is a rational integer, then . This congruence is used to show that a codimension-2 locally flat submanifold of cohomology complex projective n-space fixed by g must have degree one if m≠4 or 10 and n<?(m)+4. 相似文献
12.
Xiaolan Yu 《Journal of Mathematical Analysis and Applications》2011,376(2):535-539
For Liénard systems , with fm and gn real polynomials of degree m and n respectively, in [H. Zoladek, Algebraic invariant curves for the Liénard equation, Trans. Amer. Math. Soc. 350 (1998) 1681-1701] the author showed that if m?3 and m+1<n<2m there always exist Liénard systems which have a hyperelliptic limit cycle. Llibre and Zhang [J. Llibre, Xiang Zhang, On the algebraic limit cycles of Liénard systems, Nonlinearity 21 (2008) 2011-2022] proved that the Liénard systems with m=3 and n=5 have no hyperelliptic limit cycles and that there exist Liénard systems with m=4 and 5<n<8 which do have hyperelliptic limit cycles. So, it is still an open problem to characterize the Liénard systems which have an algebraic limit cycle in cases m>4 and m+1<n<2m. In this paper we will prove that there exist Liénard systems with m=5 and m+1<n<2m which have hyperelliptic limit cycles. 相似文献
13.
Patrick Morton 《Journal of Number Theory》2006,120(2):234-271
New explicit formulas are given for the supersingular polynomial ssp(t) and the Hasse invariant of an elliptic curve E in characteristic p. These formulas are used to derive identities for the Hasse invariants of elliptic curves En in Tate normal form with distinguished points of order n. This yields a proof that and are projective invariants (mod p) for the octahedral group and the icosahedral group, respectively; and that the set of fourth roots λ1/4 of supersingular parameters of the Legendre normal form Y2=X(X−1)(X−λ) in characteristic p has octahedral symmetry. For general n?4, the field of definition of a supersingular En is determined, along with the field of definition of the points of order n on En. 相似文献
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In this paper, the authors give a counterexample to show that the classical dyadic Hausdorff capacity on Rn when n?2 and 0<d?n−1 is not a capacity in the sense of Choquet. A variant of the classical dyadic Hausdorff capacity, , is then introduced and is further proved to be a capacity in the sense of Choquet. 相似文献
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Let be a smooth, affine variety of dimension n≥2 over the field R of real numbers. Let P be a projective A-module of such that its nth Chern class is zero. In this set-up, Bhatwadekar-Das-Mandal showed (amongst many other results) that P?A⊕Q in the case that either n is odd or the topological space X(R) of real points of X does not have a compact, connected component. In this paper, we prove that similar results hold for smooth, affine varieties over an Archimedean real closed field . 相似文献
18.
Douglas S. Stones 《Journal of Combinatorial Theory, Series A》2010,117(2):204-215
A k×n Latin rectangle on the symbols {1,2,…,n} is called reduced if the first row is (1,2,…,n) and the first column is T(1,2,…,k). Let Rk,n be the number of reduced k×n Latin rectangles and m=⌊n/2⌋. We prove several results giving divisors of Rk,n. For example, (k−1)! divides Rk,n when k?m and m! divides Rk,n when m<k?n. We establish a recurrence which determines the congruence class of for a range of different t. We use this to show that Rk,n≡((−1)k−1(k−1)!)n−1. In particular, this means that if n is prime, then Rk,n≡1 for 1?k?n and if n is composite then if and only if k is larger than the greatest prime divisor of n. 相似文献
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Enrique Arrondo 《Journal of Pure and Applied Algebra》2011,215(3):201-220
The purpose of this paper is to relate the variety parameterizing completely decomposable homogeneous polynomials of degree d in n+1 variables on an algebraically closed field, called , with the Grassmannian of (n−1)-dimensional projective subspaces of Pn+d−1. We compute the dimension of some secant varieties to . Moreover by using an invariant embedding of the Veronese variety into the Plücker space, we are able to compute the intersection of G(n−1,n+d−1) with , some of its secant varieties, the tangential variety and the second osculating space to the Veronese variety. 相似文献