共查询到20条相似文献,搜索用时 46 毫秒
1.
Florian Ivorra 《Mathematische Zeitschrift》2010,265(1):221-247
For geometrical triangulated motives with rational coefficients over a ground field of characteristic zero which is embeddable
into
\mathbbC{\mathbb{C}} , Huber (J. Algebraic Geom. 9(4):755–799, 2000; J. Algebraic Geom. 13(1):195–207, 2004) has constructed a realization functor
with values in the category of mixed realization of Huber (Mixed motives and their realization in derived categories. Lecture
Notes in Mathematics, vol. 1604. Springer, Berlin, 1995). In this sequel to Ivorra (Doc Math 12:607–671, 2007), we prove that
the ℓ-adic realization functor obtained in Theorem 4.3 of Ivorra (Doc Math 12:607–671, 2007) is the same up to a canonical isomorphism
as the ℓ-adic component of A. Huber’s construction. In this way (Ivorra in Doc Math 12:607–671, 2007) might be viewed as an integral
generalization to all noetherian separed schemes of the work (Huber in J. Algebraic Geom. 9(4):755–799, 2000; J. Algebraic
Geom. 13(1):195–207, 2004) as far as the ℓ-adic setting is concerned. We also prove a comparison theorem with the classical ℓ-adic cycle class map over a perfect field using a naive motivic cycle class map. 相似文献
2.
Complete (n,r)-arcs in PG(k−1,q) and projective (n,k,n−r)
q
-codes that admit no projective extensions are equivalent objects. We show that projective codes of reasonable length admit
only projective extensions. Thus, we are able to prove the maximality of many known linear codes. At the same time our results
sharply limit the possibilities for constructing long non-linear codes. We also show that certain short linear codes are maximal.
The methods here may be just as interesting as the results. They are based on the Bruen–Silverman model of linear codes (see
Alderson TL (2002) PhD. Thesis, University of Western Ontario; Alderson TL (to appear) J Combin Theory Ser A; Bruen AA, Silverman
R (1988) Geom Dedicata 28(1): 31–43; Silverman R (1960) Can J Math 12: 158–176) as well as the theory of Rédei blocking sets
first introduced in Bruen AA, Levinger B (1973) Can J Math 25: 1060–1065.
相似文献
3.
Sergio Conti Georg Dolzmann 《Calculus of Variations and Partial Differential Equations》2009,34(4):531-551
We derive a two-dimensional model for elastic plates as a Γ-limit of three-dimensional nonlinear elasticity with the constraint
of incompressibility. The resulting model describes plate bending, and is determined from the isochoric elastic moduli of
the three-dimensional problem. Without the constraint of incompressibility, a plate theory was first derived by Friesecke
et al. (Comm Pure Appl Math 55:1461–1506, 2002). We extend their result to the case of p growth at infinity with p ϵ [1, 2), and to the case of incompressible materials. The main difficulty is the construction of a recovery sequence which
satisfies the nonlinear constraint pointwise. One main ingredient is the density of smooth isometries in W
2,2 isometries, which was obtained by Pakzad (J Differ Geom 66:47–69, 2004) for convex domains and by Hornung (Comptes Rendus
Mathematique 346:189–192, 2008) for piecewise C
1 domains. 相似文献
4.
Michael Huber 《Journal of Algebraic Combinatorics》2007,26(4):453-476
As a consequence of the classification of the finite simple groups, it has been possible in recent years to characterize Steiner
t-designs, that is t-(v,k,1) designs, mainly for t=2, admitting groups of automorphisms with sufficiently strong symmetry properties. However, despite the finite simple group
classification, for Steiner t-designs with t>2 most of these characterizations have remained long-standing challenging problems. Especially, the determination of all
flag-transitive Steiner t-designs with 3≤t≤6 is of particular interest and has been open for about 40 years (cf. Delandtsheer (Geom. Dedicata 41, p. 147, 1992 and Handbook of Incidence Geometry, Elsevier Science, Amsterdam, 1995, p. 273), but presumably dating back to 1965).
The present paper continues the author’s work (see Huber (J. Comb. Theory Ser. A 94, 180–190, 2001; Adv. Geom. 5, 195–221, 2005; J. Algebr. Comb., 2007, to appear)) of classifying all flag-transitive Steiner 3-designs and 4-designs. We give a complete classification of all
flag-transitive Steiner 5-designs and prove furthermore that there are no non-trivial flag-transitive Steiner 6-designs. Both
results rely on the classification of the finite 3-homogeneous permutation groups. Moreover, we survey some of the most general
results on highly symmetric Steiner t-designs.
相似文献
5.
Brant C. Jones 《Journal of Algebraic Combinatorics》2009,29(2):229-260
We show that the leading coefficient of the Kazhdan–Lusztig polynomial P
x,w
(q) known as μ(x,w) is always either 0 or 1 when w is a Deodhar element of a finite Weyl group. The Deodhar elements have previously been characterized using pattern avoidance
in Billey and Warrington (J. Algebraic Combin. 13(2):111–136, [2001]) and Billey and Jones (Ann. Comb. [2008], to appear). In type A, these elements are precisely the 321-hexagon avoiding permutations. Using Deodhar’s algorithm (Deodhar in Geom. Dedicata
63(1):95–119, [1990]), we provide some combinatorial criteria to determine when μ(x,w)=1 for such permutations w.
The author received support from NSF grants DMS-9983797 and DMS-0636297. 相似文献
6.
Yoshinobu Kamishima 《Geometriae Dedicata》2006,122(1):33-49
Long and Reid [Algebr. Geom. Topol. 2: 285–296, 2002] have shown that the diffeomorphism class of every Riemannian flat manifold
of dimension n≥ 3 arises as a cusp cross-section of a complete finite volume real hyperbolic (n+1)-orbifold. For the complex hyperbolic case, McReynolds [Algebr. Geom. Topol. 4: 721–755, 2004] proved that every 3-dimensional
infranilmanifold is diffeomorphic to a cusp cross-section of a complete finite volume complex hyperbolic 2-orbifold. Moreover,
he gave a necessary and sufficient condition for a Heisenberg infranilmanifold to be realized as a cusp cross-section of finite
volume (arithmetically) complex hyperbolic orbifold. We study these realization problems by using Seifert fibrations. 相似文献
7.
We show that for each discrete group Γ, the rational assembly map
is injective on classes dual to , where Λ* is the subring generated by cohomology classes of degree at most 2 (and where the pairing uses the Chern character). Our
result implies homotopy invariance of higher signatures associated to classes in Λ*. This consequence was first established by Connes–Gromov–Moscovici (Geom. Funct. Anal. 3(1): 1–78, 1993) and Mathai (Geom.
Dedicata 99: 1–15, 2003). Note, however that the above injectivity statement does not follow from their methods. Our approach
is based on the construction of flat twisting bundles out of sequences of almost flat bundles as first described in our work
(Hanke and Schick, J. Differential Geom. 74: 293–320, 2006). In contrast to the argument in Connes-Gromov-Moscovici (Geom.
Funct.Anal. 3(1): 1–78, 1993), our approach is independent of (and indeed gives a new proof of) the result of Hilsum–Skandalis
(J. Reine Angew. Math. 423: 73–99, 1999) on the homotopy invariance of the index of the signature operator twisted with bundles
of small curvature.
相似文献
8.
Esther Ezra 《Discrete and Computational Geometry》2011,45(1):45-64
We show that the combinatorial complexity of the union of n infinite cylinders in ℝ3, having arbitrary radii, is O(n
2+ε
), for any ε>0; the bound is almost tight in the worst case, thus settling a conjecture of Agarwal and Sharir (Discrete Comput. Geom.
24:645–685, 2000), who established a nearly-quadratic bound for the restricted case of nearly congruent cylinders. Our result extends, in a significant way, the result of Agarwal and Sharir (Discrete Comput. Geom. 24:645–685, 2000), in particular, a simple specialization of our analysis to the case of nearly congruent cylinders yields a nearly-quadratic
bound on the complexity of the union in that case, thus significantly simplifying the analysis in Agarwal and Sharir (Discrete
Comput. Geom. 24:645–685, 2000). Finally, we extend our technique to the case of “cigars” of arbitrary radii (that is, Minkowski sums of line-segments and
balls) and show that the combinatorial complexity of the union in this case is nearly-quadratic as well. This problem has
been studied in Agarwal and Sharir (Discrete Comput. Geom. 24:645–685, 2000) for the restricted case where all cigars have (nearly) equal radii. Based on our new approach, the proof follows almost
verbatim from the analysis for infinite cylinders and is significantly simpler than the proof presented in Agarwal and Sharir
(Discrete Comput. Geom. 24:645–685, 2000). 相似文献
9.
A general method for constructing logarithmic modules in vertex operator algebra theory is presented. By utilizing this approach,
we give explicit vertex operator construction of certain indecomposable and logarithmic modules for the triplet vertex algebra
W(p){\mathcal{W}(p)} and for other subalgebras of lattice vertex algebras and their N = 1 super extensions. We analyze in detail indecomposable modules obtained in this way, giving further evidence for the conjectural
equivalence between the category of W(p){\mathcal{W}(p)}-modules and the category of modules for the restricted quantum group [`(U)]q(sl2){\overline{\mathcal{U}}_q(sl_2)} , q = e
π
i/p
. We also construct logarithmic representations for a certain affine vertex operator algebra at admissible level realized
in Adamović (J. Pure Appl. Algebra 196:119–134, 2005). In this way we prove the existence of the logarithmic representations
predicted in Gaberdiel (Int. J. Modern Phys. A 18, 4593–4638, 2003). Our approach enlightens related logarithmic intertwining
operators among indecomposable modules, which we also construct in the paper. 相似文献
10.
Nikias De Feyter 《Designs, Codes and Cryptography》2007,43(1):21-32
In De Clerck and Delanote (Des. Codes Cryptogr, 32: 103–110, 2004) it is shown that if a (0,α)-geometry with α ≥ 3 is fully
embedded in AG (n,q) then it is a linear representation. In De Feyter (J. Combin Theory Ser A, 109(1): 1–23, 2005; Discrete math, 292: 45–54,
2005) the (0,2)-geometries fully embedded in AG(3,q) are classified apart from two open cases. In this paper, we solve these two open cases. This classification for AG(3,q) is used in De Feyter (Adv Geom, 5: 279–292, 2005) to classify the (0,2)-geometries fully embedded in AG(n,q).
相似文献
11.
We show that the natural “convolution” on the space of smooth, even, translation-invariant convex valuations on a euclidean
space V, obtained by intertwining the product and the duality transform of S. Alesker J. Differential Geom. 63: 63–95, 2003; Geom.Funct.
Anal. 14:1–26, 2004 may be expressed in terms of Minkowski sum. Furthermore the resulting product extends naturally to odd
valuations as well. Based on this technical result we give an application to integral geometry, generalizing Hadwiger’s additive
kinematic formula for SO(V) Convex Geometry, North Holland, 1993 to general compact groups acting transitively on the sphere: it turns out that these formulas are in a natural sense dual to the usual (intersection)
kinematic formulas.
相似文献
12.
Miodrag Soki? 《Order》2012,29(1):1-30
An important problem in topological dynamics is the calculation of the universal minimal flow of a topological group. When
the universal minimal flow is one point, we say that the group is extremely amenable. For the automorphism group of Fra?ssé
structures, this problem has been translated into a question about the Ramsey and ordering properties of certain classes of
finite structures by Kechris et al. (Geom Funct Anal 15:106–189, 2005). Using the Schmerl list (Schmerl, Algebra Univers 9:317–321, 1979) of Fra?ssé posets, we consider classes of finite posets with arbitrary linear orderings and linear orderings that are linear
extensions of the partial ordering. We provide classification of each of these classes according to their Ramsey and ordering
properties. Additionally, we extend the list of extremely amenable groups as well as the list of metrizable universal minimal
flows. 相似文献
13.
Pointwise Approximation Theorems for Combinations
and Derivatives of Bernstein Polynomials 总被引:1,自引:0,他引:1
Lin Sen XIE 《数学学报(英文版)》2005,21(5):1241-1248
We establish the pointwise approximation theorems for the combinations of Bernstein polynomials by the rth Ditzian-Totik modulus of smoothness wФ^r(f, t) where Ф is an admissible step-weight function. An equivalence relation between the derivatives of these polynomials and the smoothness of functions is also obtained. 相似文献
14.
Endre Boros Khaled Elbassioni Vladimir Gurvich Hans Raj Tiwary 《Annals of Operations Research》2011,188(1):63-76
Given a graph G=(V,E) and a weight function on the edges w:E→ℝ, we consider the polyhedron P(G,w) of negative-weight flows on G, and get a complete characterization of the vertices and extreme directions of P(G,w). Based on this characterization, and using a construction developed in Khachiyan et al. (Discrete Comput. Geom. 39(1–3):174–190,
2008), we show that, unless P=NP, there is no output polynomial-time algorithm to generate all the vertices of a 0/1-polyhedron. This strengthens the NP-hardness
result of Khachiyan et al. (Discrete Comput. Geom. 39(1–3):174–190, 2008) for non 0/1-polyhedra, and comes in contrast with the polynomiality of vertex enumeration for 0/1-polytopes (Bussiech and
Lübbecke in Comput. Geom., Theory Appl. 11(2):103–109, 1998). As further applications, we show that it is NP-hard to check if a given integral polyhedron is 0/1, or if a given polyhedron
is half-integral. Finally, we also show that it is NP-hard to approximate the maximum support of a vertex of a polyhedron
in ℝ
n
within a factor of 12/n. 相似文献
15.
An essential cycle on a surface is a simple cycle that cannot be continuously deformed to a point or a single boundary. We
describe algorithms to compute the shortest essential cycle in an orientable combinatorial surface in O(n
2log n) time, or in O(nlog n) time when both the genus and number of boundaries are fixed. Our results correct an error in a paper of Erickson and Har-Peled
(Discrete Comput. Geom. 31(1):37–59, 2004). 相似文献
16.
In a paper by Cook and Reckhow (1979), it is shown that any two classical Frege systems polynomially simulate each other.
The same proof does not work for intuitionistic Frege systems, since they can have nonderivable admissible rules. (The rule
A/B is derivable if the formula A → B is derivable. The rule A/B is admissible if for all substitutions σ, if σ(A) is derivable,
then σ(B) is derivable.) In this paper, we polynomially simulate a single admissible rule. Therefore any two intuitionistic
Frege systems polynomially simulate each other. Bibliography: 20 titles.
Published in Zapiski Nauchnykh Seminarov POMI, Vol. 316, 2004, pp. 129–146. 相似文献
17.
Kevin Whyte showed that all Baumslag–Solitar groups BS(p,q) with 1 < p < q are quasi-isometric [Whyte, K., Geom. Funct. Anal. 11 (2001), 1327–1343]. We provide an elementary geometric proof. 相似文献
18.
Selçuk Demir 《Geometriae Dedicata》2004,105(1):189-207
Let G denote the isometry group of a regular tree of degree ≥3. The notion of congruence subgroup is introduced and finite generation
of the congruence Hecke algebras is proven. Let U be congruence subgroup and
(G; U) be the category of smooth representations of G generated by their U-fixed vectors. We also show that this subcategory is closed under taking subquotients. All these results are analogues of
well-known results in the case of p-adic groups. It is also shown that the category of admissible representation of G is Noetherian in the sense that every subrepresentation of a finitely generated admissible representation is again finitely
generated. Since we want to emphesize the similarities between these groups and p-adic groups, we give the same proofs which also work in the p-adic case whenever possible. 相似文献
19.
20.
Yves Edel 《Designs, Codes and Cryptography》2010,57(1):35-44
In this paper we characterize the d-dimensional dual hyperovals in PG(2d + 1, 2) that can be obtained by Yoshiara’s construction (Innov Incid Geom 8:147–169, 2008) from quadratic APN functions and
state a one-to-one correspondence between the extended affine equivalence classes of quadratic APN functions and the isomorphism
classes of these dual hyperovals. 相似文献