bluuebunny/crossref_metadata_2025 huggingface dataset:
Human versus virtual robotics soccer: A technical analysis
Authors: Abreu Pedro , Moreira João , Costa Israel , Castelão Daniel , Reis Luis , Garganta Júlio
Published: August 2011

Soccer is a team sport in which the performances of all team members are important for the outcome of a match. Even though the analysis of game events can be used to measure the team's performance, their perception, especially during the match, is extremely difficult, even for the involved agents. Soccer has been used as a simulation environment in many studies, mainly in the area of robotics. The RoboCup is an international robotics competition with an ambitious goal: in 2050 a robotics team will be capable of defeating the human world champion at the time. In this context, we compared technical similarities between human and robotics soccer. Based on an off‐line automatic event detection tool, game statistics for the finals of both human and robotics soccer tournaments were collected and compared using the Wilcoxon test. The results show that the most frequent event in both forms of soccer is successful passes. Analysing the two types of passes considered (successful and missed), we conclude that there are significant differences between the two forms (W = 2, P=0.000354), with human soccer presenting a higher percentage of successful passes (77.89% vs. 66.97%). Of restart events (W=0, P=0.00048965), the most frequent one, in both forms, is the throw‐in (human 59.91%, robotics 66.4%), and the least frequent is the corner (human 13.7%, robotics 14.09%). Regarding the frequency of shots, in the robotics environment “shots” were the most predominant type (43.27%), whereas in human soccer “shots on target” predominated (71.25%; W=64, P=0.000085641). Finally, the number of faults is minor in robotics soccer.
Hand–arm strength and endurance as predictors of climbing performance
Authors: Baláš Jiří , Pecha Ondřej , Martin Andrew J. , Cochrane Darryl
Published: August 2011

The aims of this study were to examine training characteristics, body composition, muscular strength, and endurance in sport climbers, and to demonstrate the relationship among these components by means of structural equation modelling. Altogether, 205 sport climbers (136 males, 69 females), with a performance RP (red point) of grade 4 to 11 on the Union Internationale des Association d'Alpinisme (UIAA) scale, took part in the study. The proposed structural model, with latent variable hand–arm strength and endurance (developed from reference values for simple tests), indicated by three manifest variables (grip strength, bent‐arm hang, and finger hang) and three exogenous variables (body fat, volume of climbing, and climbing experience), explained 97% of the variance in climbing performance. The relationship between body fat and climbing experience/volume with climbing performance was not direct, but was better explained using the mediator hand–arm strength and endurance. We conclude that these simple tests, together with percent body fat, volume of climbing, and climbing experience, can satisfactorily predict climbing performance.
Investigating the gas phase emitter effect of caesium and cerium in ceramic metal halide lamps in dependence on the operating frequency
Authors: Ruhrmann C , Westermeier M , Bergner A , Luijks G M J F , Awakowicz P , Mentel J
Published: August 2011

The work function and with it the temperature of tungsten electrodes in HID lamps can be lowered and the lifetime of lamps increased by the gas phase emitter effect. A determination of the emitter effect of Cs and Ce is performed by phase resolved measurements of the electrode tip temperature T
tip(φ), plasma temperature T
pl(φ) and particle densities N(φ) by means of pyrometric, optical emission and broadband absorption spectroscopy in dependence on the operating frequency. The investigated HID lamps are ceramic metal halide lamps with transparent discharge vessels made of YAG, filled with a buffer gas consisting of Ar, Kr and predominantly Hg and seeded with CsI or CeI3. In the YAG lamp seeded with CsI and CeI3 as well as in a YAG lamp seeded with DyI3 (corresponding results can be found in a preceding paper) a gas phase emitter effect is observed in the cathodic phase due to a Cs, Ce or Dy ion current. In the YAG lamp seeded with CsI the phase averaged coverage of the electrode surface with emitter atoms decreases and the electrode temperature rises with increasing frequency, whereas the emitter effect of Ce and Dy is extended to the anodic phase, which leads to a decreased average temperature T
tip(φ) with increasing frequency. This different behaviour of the averaged values of T
tip(φ) for increasing frequency is caused by the differing adsorption energies E
a of the respective emitter materials. In spite of the influence of E
a on the coverage of the electrode with emitter atoms, the cathodic gas phase emitter effect produces in the YAG lamps seeded with CsI, CeI3 and DyI3 a general reduction in the electrode tip temperature T
tip(φ) in comparison with a YAG lamp with Hg filling only.
Impedance and Raman spectroscopic studies of (Na0.5Bi0.5)TiO3
Authors: Barick B K , Mishra K K , Arora A K , Choudhary R N P , Pradhan Dillip K
Published: August 2011

Polycrystalline powder of (Na0.5Bi0.5)TiO3 (NBT) was prepared by a high-temperature solid-state reaction route. Preliminary x-ray diffraction analysis carried out at room temperature showed the formation of a single phase compound with a rhombohedral crystal system. Scanning electron micrograph reveals the polycrystalline nature of the material with size anisotropy. Dielectric study showed an existence of diffuse phase transition around 300 °C. The ac conductivity spectrum obeyed the Jonscher power law. The temperature dependent pre-exponential factor (A) shows peak and frequency exponent (n) possesses a minimum at transition temperature. The bulk conductivity of the material indicates an Arrhenius type of thermally activated process with three different conduction mechanisms as different activation energies are observed. The hopping charge carriers dominate at low temperature, small polaron and oxygen vacancy dominates at intermediate temperature and ionic conduction at higher temperatures. Studies of impedance spectroscopy indicate that the dielectric relaxation is of non-Debye type. In situ high-temperature Raman spectroscopy shows discontinuous changes in the phonon frequencies across the rhombohedral–tetragonal transition. In addition, anomalous changes in the intensity and the linewidth of a lattice mode are found around 350 °C.
Novel states of pre-transition edge turbulence emerging from shearing mode competition
Authors: Miki K. , Diamond P.H.
Published: August 2011

Recent experiments have noted the coexistence of multiple shearing fields in edge turbulence, and have observed that the shearing population ratios evolve as the L–H transition is approached. A novel model including zonal flows (ZFs), geodesic acoustic modes (GAMs) and turbulence as a zero-dimensional self-consistent two predator–one prey system with multiple frequency shearings is proposed. ZF with finite frequency (i.e. GAM) can have different shearing dynamics from that with zero frequency, because of the finite shearing field autocorrelation times. Decomposing the broadband ZF spectrum into the two populations enables us to assign different shearing weights to the components of the shearing field. We define states with no ZF and GAM as an L-mode-like state, that with ZF and without GAM as an ZF-only state, with GAM and without ZF as a GAM-only state and both with ZF and GAM as the coexistence state. To resolve the origins of multiple shear coexistence, mode-competition effects are introduced. These originate from higher order perturbation of wave populations. The model exhibits a sequence of transitions between various states as the net driving flux increases. For some parameters, bistability of ZF and GAM is evident, which predicts hysteretic behaviour in the turbulence intensity field during power ramp up/down studies. The presence of noise due to ambient turbulence offers a mechanism to explain the bursts and pulsations observed in the turbulence field prior to the L–H transition.
Environmental and economic assessments of magnetic and inertial fusion energy reactors
Authors: Yamazaki K. , Oishi T. , Mori K.
Published: August 2011

Global warming due to rapid greenhouse gas (GHG) emissions is one of the present-day crucial problems, and fusion reactors are expected to be abundant electric power generation systems to reduce human GHG emission amounts. To search for an environmental-friendly and economical fusion reactor system, comparative system studies have been done for several magnetic fusion energy reactors, and have been extended to include inertial fusion energy reactors. We clarify new scaling formulae for the cost of electricity and GHG emission rate with respect to key design parameters, which might be helpful in making a strategy for fusion research development. Comparisons with other conventional electric power generation systems are carried out taking into account the introduction of GHG taxes and the application of the carbon dioxide capture and storage system to fossil power generators.
Construction of low rank vector bundles on 𝐏⁴ and 𝐏⁵
Authors: Kumar N. , Peterson Chris , Rao A.
Published: August 2011

We describe a technique which permits a uniform construction of a number of low rank bundles, both known and new. In characteristic two, we obtain rank two bundles on

P

5

\mathbf {P}^{5}

. In characteristic

p
p

, we obtain rank two bundles on

P

4

\mathbf {P}^4

and rank three bundles on

P

5

\mathbf {P}^5

. In arbitrary characteristic, we obtain rank three bundles on

P

4

\mathbf {P}^4

and rank two bundles on the quadric

S
5

S_5

in

P

6

\mathbf {P}^6

.
Deformation of Okamoto–Painlevé pairs and Painlevé equations
Authors: Saito Masa-Hiko , Takebe Taro , Terajima Hitomi
Published: August 2011

In this paper, we introduce the notion of a generalized rational Okamoto–Painlevé pair

(
S
,
Y
)

(S, Y)

by generalizing the notion of the spaces of initial conditions of Painlevé equations. After classifying those pairs, we will establish an algebro-geometric approach to derive the Painlevé differential equations from the deformation of Okamoto–Painlevé pairs by using the local cohomology groups. Moreover the reason why the Painlevé equations can be written in Hamiltonian systems is clarified by means of the holomorphic symplectic structure on

S
−
Y

S - Y

. Hamiltonian structures for Okamoto–Painlevé pairs of type

E
~

7

(
=

P

I
I

)

\tilde {E}_7 (= P_{II})

and

D
~

8

(
=

P

I
I
I

D
~

8

)

\tilde {D}_8 (= P_{III}^{\tilde {D}_8})

are calculated explicitly as examples of our theory.
Arakelov type inequalities for Hodge bundles over algebraic varieties, Part I: Hodge bundles over algebraic curves
Authors: Jost Jürgen , Zuo Kang
Published: August 2011

We prove Arakelov inequalities for systems of Hodge bundles over algebraic varieties, generalizing the classical ones for families of semi-stable curves and abelian varieties. These inequalities are derived from the semi-stability of an associated Higgs bundle, a consequence of the existence of a Hermitian Yang-Mills metric.
Dynamics of the Segre varieties of a real submanifold in complex space
Authors: Baouendi M. , Ebenfelt P. , Rothschild Linda
Published: August 2011

For a smooth (or formal) generic submanifold

M
M

of real codimension

d
d

in complex space

C

N

\mathbb {C}^N

with

0
∈
M

0\in M

, we introduce the notion of a formal Segre variety mapping
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="gamma colon left-parenthesis double-struck upper C Superscript upper N Baseline times double-struck upper C Superscript upper N minus d Baseline comma 0 right-parenthesis right-arrow left-parenthesis double-struck upper C Superscript upper N Baseline comma 0 right-parenthesis">

γ
:
(

C

N

×

C

N
−
d

,
0
)
→
(

C

N

,
0
)

\gamma : (\mathbb {C}^N\times \mathbb {C} ^{N-d},0)\to (\mathbb {C}^N,0)

and its iterated Segre mappings at

0
0

,
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="v Superscript j Baseline colon left-parenthesis double-struck upper C Superscript left-parenthesis upper N minus d right-parenthesis j Baseline comma 0 right-parenthesis right-arrow left-parenthesis double-struck upper C Superscript upper N Baseline comma 0 right-parenthesis">

v
j

:
(

C

(
N
−
d
)
j

,
0
)
→
(

C

N

,
0
)

v^j:(\mathbb {C}^{(N-d)j},0) \to (\mathbb {C}^N,0)

,

j
≥
1

j\ge 1

. The Segre variety mapping

γ
\gamma

extends the notion of Segre varieties of a real-analytic generic submanifold to the setting of smooth (or formal) submanifolds. One of the main results in this paper is that

M
M

is of finite type (in the sense of Kohn and Bloom–Graham) at

0
0

if and only if there exists

k
0

≤
d
+
1

k_0\le d+1

such that the (generic) rank of

v

k
0

v^{k_0}

is

N
N

. More generally, we prove that

v

k
0

v^{k_0}

parameterizes the local CR orbit of

M
M

at

0
0

.
𝐾-equivalence in birational geometry and characterizations of complex elliptic genera
Authors: Wang Chin-Lung
Published: August 2011

We show that for smooth complex projective varieties the most general combinations of Chern numbers that are invariant under the

K
K

-equivalence relation consist of the complex elliptic genera.
The moduli space of cubic threefolds
Authors: Allcock Daniel
Published: August 2011

We describe the moduli space of cubic hypersurfaces inCP4\mathbb {C}P^{4}in the sense of geometric invariant theory. That is, we characterize the stable and semistable hypersurfaces in terms of their singularities, and determine the equivalence classes of semistable hypersurfaces under the equivalence relation of their orbit-closures meeting.
Finiteness of coherent cohomology for proper 𝑓𝑝𝑝𝑓 stacks
Authors: Faltings Gerd
Published: August 2011

We prove the result in the title for Noetherian fppf stacks, avoiding the use of Chow’s lemma. Instead we employ simplicial schemes and shrinking-methods.
Rational curves on general projective hypersurfaces
Authors: Pacienza Gianluca
Published: August 2011

In this article, we study the geometry of

k
k

-dimensional subvarieties with geometric genus zero of a general projective hypersurface

X
d

⊂

P

n

X_d\subset \mathbf {P}^n

of degree

d
=
2
n
−
2
−
k

d=2n-2-k

, where

k
k

is an integer such that

1
≤
k
≤
n
−
5

1\leq k\leq n-5

. As a corollary of our main result, we obtain that the only rational curves lying on the general hypersuface

X

2
n
−
3

⊂

P

n

X_{2n-3}\subset \mathbf {P}^n

, for

n
≥
6
,

n\geq 6,

are the lines.
Composantes de petite codimension du lieu de Noether-Lefschetz: Un argument asymptotique en faveur de la conjecture de Hodge pour les hypersurfaces
Authors: Otwinowska Ania
Published: August 2011

This paper gives an asymptotic description of the Noether-Lefschetz locus for smooth projective hypersurfaces in

P

C

2
n
+
1

\mathbb {P}^{2n+1}_{\mathbb {C}}

of large degree. I prove that successive small codimensional components of this locus correspond to surfaces containing a small degree subvariety of dimension

n
n

. This result generalises the work of Green and Voisin for surfaces in

P

C

3

\mathbb {P}^3_{\mathbb {C}}

containing a line and a conic.

Résumé Cet article donne une description asymptotique du lieu de Noether-Lefschetz pour les hypersurfaces lisses de grand degré dans

P

C

2
n
+
1

\mathbb {P}^{2n+1}_{\mathbb {C}}

: les composantes succéssives de plus petite codimension de ce lieu sont constituées par les hypersurfaces contenant une sous-variété de dimension

n
n

et de petit degré. Ce résultat généralise les travaus de Green et Voisin sur les surfaces de

P

C

3

\mathbb {P}^3_{\mathbb {C}}

contenant une droite et une conique.
On the existence of Enriques-Fano threefolds of index greater than one
Authors: Giraldo Luis , Lopez Angelo , Muñoz Roberto
Published: August 2011

Let

X
⊂

P

N

X \subset \mathbb {P}^{N}

be an irreducible threefold having a hyperplane section

Y
Y

that is a smooth Enriques surface and such that

X
X

is not a cone over

Y
Y

. In 1938 Fano claimed a classification of such threefolds; however, due to gaps in his proof, the problem still remains open. In this article we solve the case when

Y
Y

is the

r
r

-th Veronese embedding, for

r
≥
2

r \geq 2

, of another Enriques surface, by proving that there are no such

X
X

. The latter is achieved, among other things, by a careful study of trisecant lines to Enriques surfaces. As another consequence we get precise information on the ideal of an Enriques surface. In a previous paper we had proved that any smooth linearly normal Enriques surface has homogeneous ideal generated by quadrics and cubics. Here we are able to specify when the quadrics are enough, at least scheme-theoretically.
Regularity on abelian varieties II: Basic results on linear series and defining equations
Authors: Pareschi Giuseppe , Popa Mihnea
Published: August 2011

We apply the theory of

M
M

-regularity developed by the authors [Regularity on abelian varieties, I, J. Amer. Math. Soc. 16 (2003), 285–302] to the study of linear series given by multiples of ample line bundles on abelian varieties. We define an invariant of a line bundle, called

M
M

-regularity index, which governs the higher order properties and (partly conjecturally) the defining equations of such embeddings. We prove a general result on the behavior of the defining equations and higher syzygies in embeddings given by multiples of ample bundles whose base locus has no fixed components, extending a conjecture of Lazarsfeld [proved in Syzygies of abelian varieties, J. Amer. Math. Soc. 13 (2000), 651–664]. This approach also unifies essentially all the previously known results in this area, and is based on Fourier-Mukai techniques rather than representations of theta groups.
Some schemes related to the commuting variety
Authors: Knutson Allen
Published: August 2011

The commuting variety is the pairs of

n
×
n

n\times n

matrices

(
X
,
Y
)

(X,Y)

such that

X
Y
=
Y
X

XY=YX

. We introduce the diagonal commutator scheme,

{

(
X
,
Y
)
:
X
Y
−
Y
X

\big \{ (X,Y) : XY-YX

is diagonal

}

\big \}

, which we prove to be a reduced complete intersection, one component of which is the commuting variety. (We conjecture there to be only one other component.) The diagonal commutator scheme has a flat degeneration to the scheme

{

(
X
,
Y
)
:
X
Y

\big \{ (X,Y) : XY

lower triangular,

Y
X

YX

upper triangular

}

\big \}

, which is again a reduced complete intersection, this time with

n
!

n!

components (one for each permutation). The degrees of these components give interesting invariants of permutations.
Links and analytic invariants of superisolated singularities
Authors: Luengo-Velasco I. , Melle-Hernández A. , Némethi A.
Published: August 2011

Using superisolated singularities we present examples and counterexamples to some of the most important conjectures regarding invariants of normal surface singularities. More precisely, we show that the “Seiberg-Witten invariant conjecture”(of Nicolaescu and the third author), the “Universal abelian cover conjecture” (of Neumann and Wahl) and the “Geometric genus conjecture” fail (at least at that generality in which they were formulated). Moreover, we also show that for Gorenstein singularities (even with integral homology sphere links) besides the geometric genus, the embedded dimension and the multiplicity (in particular, the Hilbert-Samuel function) also fail to be topological; and in general, the Artin cycle does not coincide with the maximal (ideal) cycle.
Holomorphic maps onto varieties of non-negative Kodaira dimension
Authors: Hwang Jun-Muk , Kebekus Stefan , Peternell Thomas
Published: August 2011

A classical result in complex geometry says that the automorphism group of a manifold of general type is discrete. It is more generally true that there are only finitely many surjective morphisms between two fixed projective manifolds of general type. Rigidity of surjective morphisms, and the failure of a morphism to be rigid have been studied by a number of authors in the past. The main result of this paper states that surjective morphisms are always rigid, unless there is a clear geometric reason for it. More precisely, we can say the following.

First, deformations of surjective morphisms between normal projective varieties are unobstructed unless the target variety is covered by rational curves.

Second, if the target is not covered by rational curves, then surjective morphisms are infinitesimally rigid, unless the morphism factors via a variety with positive-dimensional automorphism group. In this case, the Hom-scheme can be completely described.
On automorphisms of Danielewski surfaces
Authors: Crachiola Anthony
Published: August 2011

Let

k

\mathbf {k}

be any field. Let
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper R equals bold k left-bracket upper X comma upper Y comma upper Z right-bracket slash left-parenthesis upper X Superscript n Baseline upper Y minus upper Z squared minus h left-parenthesis upper X right-parenthesis upper Z right-parenthesis">

R
=

k

[
X
,
Y
,
Z
]

/

(

X
n

Y
−

Z
2

−
h
(
X
)
Z
)

R = \mathbf {k}[X,Y,Z]/(X^n Y - Z^2 - h(X)Z)

, where

h
(
0
)
≠
0

h(0) \ne 0

and

n
≥
2

n \geq 2

. We develop techniques for computing the AK invariant of a domain with arbitrary characteristic. We use these techniques to compute

AK
⁡
(
R
)

\operatorname {AK}(R)

, describe the automorphism group of

R
R

, and describe the isomorphism classes of these algebras. We then show that these algebras provide counterexamples to the cancellation problem over any field, extending Danielewski’s original counterexample.
Classification of primary ℚ-Fano threefolds with anti-canonical Du Val 𝕂3 surfaces, I
Authors: Takagi Hiromichi
Published: August 2011

If a non-Gorenstein

Q

\mathbb {Q}

-Fano threefold with only cyclic quotient terminal singularities has anti-canonical Du Val

K
3

K3

surfaces and the anti-canonical class generates the group of numerical equivalence classes of divisors, then the dimension of the space of global sections of the anti-canonical sheaf is shown to be not greater than ten. Such

Q

\mathbb {Q}

-Fano threefolds with the dimension not less than nine are classified.
Moduli of complexes on a proper morphism
Authors: Lieblich Max
Published: August 2011

Given a proper morphism

X
→
S

X\to S

, we show that a large class of objects in the derived category of

X
X

naturally form an Artin stack locally of finite presentation over

S
S

. This class includes

S
S

-flat coherent sheaves and, more generally, contains the collection of all

S
S

-flat objects which can appear in the heart of a reasonable sheaf of

t
t

-structures on

X
X

. In this sense, this is the Mother of all Moduli Spaces (of sheaves). The proof proceeds by studying the finite presentation properties, deformation theory, and Grothendieck existence theorem for objects in the derived category, and then applying Artin’s representability theorem.
Construction of rational surfaces of degree 12 in projective fourspace
Authors: Abo Hirotachi , Ranestad Kristian
Published: August 2011

The aim of this paper is to present a construction of smooth rational surfaces in projective fourspace with degree

12
12

and sectional genus

13
13

. In particular, we establish the existences of five different families of smooth rational surfaces in projective fourspace with the prescribed invariants.
The Betti numbers of \overline{ℳ}_{0,𝓃}(𝓇,𝒹)
Authors: Getzler Ezra , Pandharipande Rahul
Published: August 2011

We calculate the Betti numbers of the coarse moduli space of stable maps of genus 0 to projective space, using a generalization of the Legendre transform.
Groupe de Picard et groupe de Brauer des compactifications lisses d’espaces homogènes
Authors: Colliot-Thélène Jean-Louis , Kunyavskiĭ Boris
Published: August 2011

Let

k
k

be a field of characteristic zero,

G
G

a connected linear algebraic group over

k
k

and

H
H

a connected closed

k
k

-subgroup of

G
G

. Let

X
X

be a smooth

k
k

-compactification of

Y
=
G

/

H

Y=G/H

. We prove that the Galois lattice given by the geometric Picard group of

X
X

is flasque. The result was known in the case

H
=
1

H=1

. We compute this Galois lattice up to addition of a permutation module. When

G
G

is semisimple and simply connected, the result shows that the Brauer group of

X
X

is determined by the maximal toric quotient of

H
H

.
Deforming 𝑙-adic representations of the fundamental group of a smooth variety
Authors: Pridham J.
Published: August 2011

There has long been a philosophy that every deformation problem in characteristic zero should be governed by a differential graded Lie algebra (DGLA). This paper develops the theory of Simplicial Deformation Complexes (SDCs) as an alternative to DGLAs. These work in all characteristics, and for many problems can be constructed canonically. This theory is applied to study the deformation functor for representations of the étale fundamental group of a variety

X
X

. We are chiefly concerned with establishing an algebraic analogue of a result proved by Goldman and Millson for compact Kähler manifolds. By applying the Weil Conjectures instead of Hodge theory, we see that if

X
X

is a smooth proper variety defined over a finite field, and we consider deformations of certain continuous

l
l

-adic representations of the algebraic fundamental group, then the hull of the deformation functor will be defined by quadratic equations. Moreover, if

X
X

is merely smooth, then the hull will be defined by equations of degree at most four.
Rationally connected foliations after Bogomolov and McQuillan
Authors: Kebekus Stefan , Conde Luis , Toma Matei
Published: August 2011

This paper is concerned with sufficient criteria to guarantee that a given foliation on a normal variety has algebraic and rationally connected leaves. Following ideas from a preprint of Bogomolov and McQuillan and using the recent work of Graber, Harris, and Starr, we give a clean, short and simple proof of previous results. Apart from a new vanishing theorem for vector bundles in positive characteristic, our proof employs only standard techniques of Mori theory and does not make any reference to the more involved properties of foliations in characteristic

p
p

.

We also give a new sufficient condition to ensure that all leaves are algebraic.

The results are then applied to show that

Q

\mathbb Q

-Fano varieties with unstable tangent bundles always admit a sequence of partial rational quotients naturally associated to the Harder-Narasimhan filtration.
Linear systems in ℙ² with base points of bounded multiplicity
Authors: Yang Stephanie
Published: August 2011

We present a proof of the Harbourne-Hirschowitz conjecture for linear systems with multiple points of order

7
7

or less. This uses a well-known degeneration of the plane developed by Ciliberto and Miranda as well as a combinatorial game that arises from specializing points onto lines.
On the invariance and the lower semi-continuity of plurigenera of algebraic varieties
Authors: Takayama Shigeharu
Published: August 2011

We state the invariance and the lower semi-continuity of plurigenera for certain families of algebraic varieties.
Pfaffian lines and vector bundles on Fano threefolds of genus 8
Authors: Iliev Atanas , Manivel Laurent
Published: August 2011

LetXXbe a general complex Fano threefold of genus88. We prove that the moduli space of rank two semistable sheaves onXXwith Chern numbersc1=1c_1=1,c2=6c_2=6andc3=0c_3=0is isomorphic to the Fano surfaceF(X)F(X)of conics onXX. This surface is smooth and isomorphic to the Fano surface of lines in the orthogonal toXXcubic threefold. InsideF(X)F(X), the nonlocally free sheaves are parameterized by a smooth curve of genus2626isomorphic to the base of the family of lines onX\textrm {X}.
A formula for non-equioriented quiver orbits of type 𝐴
Authors: Buch Anders , Rimányi Richárd
Published: August 2011

We prove a positive combinatorial formula for the equivariant class of an orbit closure in the space of representations of an arbitrary quiver of type

A
A

. Our formula expresses this class as a sum of products of Schubert polynomials indexed by a generalization of the minimal lace diagrams of Knutson, Miller, and Shimozono. The proof is based on the interpolation method of Fehér and Rimányi. We also conjecture a more general formula for the equivariant Grothendieck class of an orbit closure.
Gromov-Witten invariants for abelian and nonabelian quotients
Authors: Bertram Aaron , Ciocan-Fontanine Ionuţ , Kim Bumsig
Published: August 2011

Conjectural formulas are given expressing the genus zero Gromov-Witten invariants of the quotient of a complex projective manifold

X
X

by a reductive group

G
G

(the nonabelian quotient) in terms of the invariants of the quotient by a maximal torus

T
T

(the abelian quotient). The “

J
J

-function” version of the formulas is proved when

X
X

is a (generalized) flag manifold.
Chiral de Rham complex and orbifolds
Authors: Frenkel Edward , Szczesny Matthew
Published: August 2011

Suppose that a finite group

G
G

acts on a smooth complex variety

X
X

. Then this action lifts to the Chiral de Rham complex

Ω

X

ch

\Omega ^{\operatorname {ch}}_{X}

of

X
X

and to its cohomology by automorphisms of the vertex algebra structure. We define twisted sectors for

Ω

X

ch

\Omega ^{\operatorname {ch}}_{X}

(and their cohomologies) as sheaves of twisted vertex algebra modules supported on the components of the fixed-point sets

X

g

,
g
∈
G

X^{g}, g \in G

. Each twisted sector sheaf carries a BRST differential and is quasi-isomorphic to the de Rham complex of

X

g

X^{g}

. Putting the twisted sectors together with the vacuum sector and taking

G
G

-invariants, we recover the additive and graded structures of Chen-Ruan orbifold cohomology. Finally, we show that the orbifold elliptic genus is the partition function of the direct sum of the cohomologies of the twisted sectors.
Erratum to “The generalized de Rham-Witt complex over a field is a complex of zero-cycles”
Authors: Rülling Kay
Published: August 2011

We fill a gap in the Proof of Theorem 3.6 (J. Algebraic Geom. 16 (2007), 109–169) by modifying the definition of the residue map given in Definition 2.15 (J. Algebraic Geom. 16 (2007), 109–169) and by using a result of Hübel and Kunz.
A Kleiman–Bertini theorem for sheaf tensor products
Authors: Miller Ezra , Speyer David
Published: August 2011

Fix a variety

X
X

with a transitive (left) action by an algebraic group 

G
G

. Let

E

\mathcal {E}

and

F

\mathcal {F}

be coherent sheaves on 

X
X

. We prove that for elements

g
g

in a dense open subset of 

G
G

, the sheaf

T

o

r
i
X

(

E

,
g

F

)

\mathcal {T}\hspace {-.7ex}or^X_i(\mathcal {E}, g \mathcal {F})

vanishes for all

i
>
0

i > 0

. When

E

\mathcal {E}

and

F

\mathcal {F}

are structure sheaves of smooth subschemes of

X
X

in characteristic zero, this follows from the Kleiman–Bertini theorem; our result has no smoothness hypotheses on the supports of

E

\mathcal {E}

or 

F

\mathcal {F}

, or hypotheses on the characteristic of the ground field.
𝑆𝐿(2)-orbit theorem for degeneration of mixed Hodge structure
Authors: Kato Kazuya , Nakayama Chikara , Usui Sampei
Published: August 2011

Cattani, Kaplan and Schmid (1986) established the

SL
⁡
(
2
)

\operatorname {SL}(2)

-orbit theorem in several variables for the degeneration of polarized Hodge structure. The aim of the present paper is to generalize it for the degeneration of mixed Hodge structure whose graded quotients by the weight filtration are polarized. As an application, we obtain a mixed Hodge version of an estimate of the Hodge metric for the degeneration of polarized Hodge structure.
The irreducibility of the spaces of rational curves on del Pezzo surfaces
Authors: Testa Damiano
Published: August 2011

Let

X
X

be a del Pezzo surface of degree

d
≥
2

d \geq 2

. We prove that the spaces

M

0
,
0

(

X
,
β

)

\mathcal M_{0,0} \bigl ( X, \beta \bigr )

are either empty or irreducible.
Dénombrabilité des classes d’équivalences dérivées de variétés algébriques
Authors: Anel Mathieu , Toën Bertrand
Published: August 2011

Soient

S
S

un schéma affine,

X
⟶
S

X \longrightarrow S

une famille miniverselle de schémas projectifs et lisses, et

D
D

une catégorie triangulée fixée. On démontre que les points

s
∈
S

s\in S

tels que la catégorie dérivée de la fibre en

s
s

,

D

c
o
h

b

(

X

s

)

D_{coh}^{b}(X_{s})

, soit équivalente à

D
D

, forment un ensemble au plus dénombrable. Nous déduisons de cela que l’ensemble des classes d’isomorphisme des variétés complexes lisses et projectives qui possèdent une catégorie dérivée fixée est au plus dénombrable. Notre démonstration passe par la construction d’un certain préchamp classifiant les dg-catégories saturées et connexes, ainsi qu’une application des périodes allant du champ des variétés lisses et projectives vers ce préchamp, et qui à une variété associe un dg-modèle pour sa catégorie dérivée.
Pointed trees of projective spaces
Authors: Chen L. , Gibney A. , Krashen D.
Published: August 2011

We introduce a smooth projective variety

T

d
,
n

T_{d,n}

which compactifies the space of configurations of

n
n

distinct points on affine

d
d

-space modulo translation and homothety. The points in the boundary correspond to

n
n

-pointed stable rooted trees of

d
d

-dimensional projective spaces, which for

d
=
1

d = 1

, are

(
n
+
1
)

(n+1)

-pointed stable rational curves. In particular,

T

1
,
n

T_{1,n}

is isomorphic to

M
¯

0
,
n
+
1

\overline {M}_{0,n+1}

, the moduli space of such curves. The variety

T

d
,
n

T_{d,n}

shares many properties with

M
¯

0
,
n
+
1

\overline {M}_{0,n+1}

. For example, as we prove, the boundary is a smooth normal crossings divisor whose components are products of

T

d
,
i

T_{d,i}

for

i
>
n

i > n

, and it has an inductive construction analogous to but differing from Keel’s for

M
¯

0
,
n
+
1

\overline {M}_{0,n+1}

. This can be used to describe its Chow groups and Chow motive generalizing [Trans. Amer. Math. Soc. 330 (1992), 545–574]. It also allows us to compute its Poincaré polynomials, giving an alternative to the description implicit in [Progr. Math., vol. 129, Birkhäuser, 1995, pp. 401–417]. We give a presentation of the Chow rings of

T

d
,
n

T_{d,n}

, exhibit explicit dual bases for the dimension

1
1

and codimension

1
1

cycles. The variety

T

d
,
n

T_{d,n}

is embedded in the Fulton-MacPherson spaces

X
[
n
]

X[n]

for any smooth variety

X
X

, and we use this connection in a number of ways. In particular we give a family of ample divisors on

T

d
,
n

T_{d,n}

, and an inductive presentation of the Chow motive of

X
[
n
]

X[n]

. This also gives an inductive presentation of the Chow groups of

X
[
n
]

X[n]

analogous to Keel’s presentation for

M
¯

0
,
n
+
1

\overline {M}_{0,n+1}

, solving a problem posed by Fulton and MacPherson.
Level 𝑚 stratifications of versal deformations of 𝑝-divisible groups
Authors: Vasiu Adrian
Published: August 2011

Let

k
k

be an algebraically closed field of characteristic

p
>
0

p>0

. Let

c
,
d
,
m

c,d,m

be positive integers. Let

D
D

be a

p
p

-divisible group of codimension

c
c

and dimension

d
d

over

k
k

. Let

D

\mathscr {D}

be a versal deformation of

D
D

over a smooth

k
k

-scheme

A

\mathscr {A}

which is equidimensional of dimension

c
d

cd

. We show that there exists a reduced, locally closed subscheme

s

D

(
m
)

\mathfrak {s}_D(m)

of

A

\mathscr {A}

that has the following property: a point

y
∈

A

(
k
)

y\in \mathscr {A}(k)

belongs to

s

D

(
m
)
(
k
)

\mathfrak {s}_D(m)(k)

if and only if

y
∗

(

D

)
[

p
m

]

y^*(\mathscr {D})[p^m]

is isomorphic to

D
[

p
m

]

D[p^m]

. We prove that

s

D

(
m
)

\mathfrak {s}_D(m)

is regular and equidimensional of dimension

c
d
−
dim
⁡
(

A
u
t

A
u
t

(
D
[

p
m

]
)
)

cd-\dim (\pmb {\mathrm {Aut}}(D[p^m]))

. We give a proof of Traverso’s formula which for

m
≫
0

m\gg 0

computes the codimension of

s

D

(
m
)

\mathfrak {s}_D(m)

in

A

\mathscr {A}

(i.e.,

dim
⁡
(

A
u
t

A
u
t

(
D
[

p
m

]
)
)

\dim (\pmb {\mathrm {Aut}}(D[p^m]))

) in terms of the Newton polygon of

D
D

. We also provide a criterion of when

s

D

(
m
)

\mathfrak {s}_D(m)

satisfies the purity property (i.e., it is an affine

A

\mathscr {A}

-scheme). Similar results are proved for quasi Shimura

p
p

-varieties of Hodge type that generalize the special fibres of good integral models of Shimura varieties of Hodge type in unramified mixed characteristic

(
0
,
p
)

(0,p)

.
Towards the second main theorem on complements
Authors: Prokhorov Yu. , Shokurov V.
Published: August 2011

We prove the boundedness of complements modulo two conjectures: Borisov–Alexeev conjecture and effective adjunction for fibre spaces. We discuss the last conjecture and prove it in two particular cases.
Theta functions on moduli spaces of 𝐺-bundles
Authors: Faltings Gerd
Published: August 2011

We extend results on the Hitchin fibration to positive characteristics. We derive from the Verlinde formula the existence of canonical divisors on moduli space of

G
G

-bundles, first in characteristic zero and then (using the previous) also in positive characteristics. It remains open to give a geometric definition. We compute the central charge for some geometrically defined divisors.
Obstructions to deforming curves on a 3-fold, I: A generalization of Mumford’s example and an application to 𝐻𝑜𝑚 schemes
Authors: Mukai Shigeru , Nasu Hirokazu
Published: August 2011

We give a sufficient condition for a first order infinitesimal deformation of a curve on a

3
3

-fold to be obstructed. As application we construct generically non-reduced components of the Hilbert schemes of uniruled

3
3

-folds and the Hom scheme from a general curve of genus five to a general cubic

3
3

-fold.
Stability conditions and Calabi–Yau fibrations
Authors: Toda Yukinobu
Published: August 2011

In this paper, we describe the spaces of stability conditions for the triangulated categories associated to three-dimensional Calabi–Yau fibrations. We deal with two cases, the flat elliptic fibrations and smooth

K
3

K3

(Abelian) fibrations. In the first case, we will see that there exist chamber structures similar to those of the movable cone used in birational geometry. In the second case, we will compare the space with the space of stability conditions for the closed fiber of the fibration.
Non-archimedean analytification of algebraic spaces
Authors: Conrad Brian , Temkin Michael
Published: August 2011

We study quotient problems for étale equivalence relations in non- archimedean geometry, and we construct quotients for such equivalence relations in Berkovich’s category of analytic spaces, assuming a separatedness hypothesis on the equivalence relation. We also give counterexamples that show the necessity of separatedness hypotheses, in contrast with the complex-analytic case. As an application, we construct analytifications for separated algebraic spaces over a non-archimedean field.
Rational maps between moduli spaces of curves and Gieseker-Petri divisors
Authors: Farkas Gavril
Published: August 2011

We study contractions of the moduli space of stable curves beyond the minimal model ofM¯g′\overline {\mathcal {M}}_{g’}by giving a complete enumerative description of the rational map between two moduli spaces of curvesM¯g⇢M¯g′\overline {\mathcal {M}}_g \dashrightarrow \overline {\mathcal {M}}_{g’}which associates to a curveCCof genusggits Brill–Noether locus of special divisors in the case this locus is a curve. As an application we construct many examples of moving effective divisors onM¯g\overline {\mathcal {M}}_gof small slope, which in turn can be used to show that various moduli space of curves with level structure are of general type. For lowg′g’our calculation can be used to study the intersection theory of the moduli space of Prym varieties of dimension55.
Ekedahl-Oort strata contained in the supersingular locus and Deligne-Lusztig varieties
Authors: Harashita Shushi
Published: August 2011

We study the moduli space of principally polarized abelian varieties over fields of positive characteristic. In this paper we describe certain unions of Ekedahl-Oort strata contained in the supersingular locus in terms of Deligne-Lusztig varieties. As a corollary we show that each Ekedahl-Oort stratum contained in the supersingular locus is reducible except possibly for small

p
p

.
Factorial threefold hypersurfaces
Authors: Cheltsov Ivan
Published: August 2011

Let

X
X

be a hypersurface in

P

4

\mathbb {P}^{4}

of degree 

d
d

that has at worst isolated ordinary double points. We prove that

X
X

is factorial in the case when

X
X

has at most

(
d
−
1

)

2

−
1

(d-1)^{2}-1

singular points.
Corrigendum: “The Chow ring of the moduli space of abelian threefolds”
Authors: van der Geer Gerard
Published: August 2011

An inaccurate formulation in a paper on the Chow ring of the moduli of abelian threefolds is corrected.
Inducing stability conditions
Authors: Macrì Emanuele , Mehrotra Sukhendu , Stellari Paolo
Published: August 2011

We study stability conditions induced by functors between triangulated categories. Given a finite group acting on a smooth projective variety, we prove that the subset of invariant stability conditions embeds as a closed submanifold into the stability manifold of the equivariant derived category. As an application, we examine stability conditions on Kummer and Enriques surfaces and we improve the derived version of the Torelli Theorem for the latter surfaces already present in the literature. We also study the relationship between stability conditions on projective spaces and those on their canonical bundles.
On Shimura curves in the Schottky locus
Authors: Kukulies Stefan
Published: August 2011

We show that a given rational Shimura curve

Y
Y

with strictly maximal Higgs field in the moduli space of

g
g

-dimensional principally polarized abelian varieties does not map to the closure of the Schottky locus for large

g
g

if the generic point is the jacobian of a smooth curve.

We achieve this by using a result of Viehweg and Zuo which says that the corresponding family of abelian varieties over

Y
Y

is

Y
Y

-isogenous to the

g
g

-fold product of a modular family of elliptic curves. After reducing the situation from the field of complex numbers to a finite field, we will see, combining the Weil and Sato-Tate conjectures, that for large

g
g

no such family can become the jacobian of a family of curves.
Homological Mirror Symmetry for the genus two curve
Authors: Seidel Paul
Published: August 2011

We prove a form of Homological Mirror Symmetry for the genus two curve (on the symplectic or

A
A

-model side).
Foliations and rational connectedness in positive characteristic
Authors: Shen Mingmin
Published: August 2011

In this paper, the technique of foliations in characteristic

p
p

is used to investigate the difference between rational connectedness and separable rational connectedness in positive characteristic. The notion of being freely rationally connected is defined; a variety is freely rationally connected if a general pair of points can be connected by a free rational curve. It is proved that a freely rationally connected variety admits a finite purely inseparable morphism to a separably rationally connected variety. As an application, a generalized Graber-Harris-Starr type theorem in positive characteristic is proved; namely, if a family of varieties over a smooth curve has the property that its geometric generic fiber is normal and freely rationally connected, then it has a rational section after some Frobenius twisting. We also show that a freely rationally connected variety is simply connected.
Rank-level duality for conformal blocks of the linear group
Authors: Oudompheng Rémy
Published: August 2011

We generalise the rank-level duality (also known asstrange duality) proved by P. Belkale [J. Amer. Math. Soc.21(2008), no. 1, 235–258] for generic curves and A. Marian and D. Oprea [Invent. Math.168(2007), no. 2, 225–247] for every smooth curve to the case of spaces of conformal blocks related to moduli spaces of parabolic bundles on a smooth pointed projective curve.
New topological recursion relations
Authors: Liu Xiaobo , Pandharipande Rahul
Published: August 2011

Simple boundary expressions for the

k

t
h

k^{th}

power of the cotangent line class

ψ
1

\psi _1

on

M
¯

g
,
1

\overline {M}_{g,1}

are found for

k
≥
2
g

k\geq 2g

. The method is by virtual localization on the moduli space of maps to

P

1

\mathbb {P}^1

. As a consequence, nontrivial tautological classes in the kernel of the boundary push-forward map
\[
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="iota Subscript asterisk Baseline colon upper A Superscript asterisk Baseline left-parenthesis upper M overbar Subscript g comma 2 Baseline right-parenthesis right-arrow upper A Superscript asterisk Baseline left-parenthesis upper M overbar Subscript g plus 1 Baseline right-parenthesis">

ι
∗

:

A
∗

(

M
¯

g
,
2

)
→

A
∗

(

M
¯

g
+
1

)

\iota _*:A^*( \overline {M}_{g,2}) \rightarrow A^*(\overline {M}_{g+1})

\]
are constructed. The geometry of genus

g
+
1

g+1

curves, then provides universal equations in genus

g
g

Gromov-Witten theory. As an application, we prove all the Gromov-Witten identities conjectured recently by K. Liu and H. Xu.
Stable modification of relative curves
Authors: Temkin Michael
Published: August 2011

We generalize theorems of Deligne-Mumford and de Jong on semi-stable modifications of families of proper curves. The main result states that after a generically étale alteration of the base any (not necessarily proper) family of multipointed curves with semi-stable generic fiber admits a minimal semi-stable modification. The latter can also be characterized by the property that its geometric fibers have no certain exceptional components. The main step of our proof is uniformization of one-dimensional extensions of valued fields. Riemann-Zariski spaces are then used to obtain the result over any integral base.
Homogeneous interpolation on ten points
Authors: Ciliberto Ciro , Miranda Rick
Published: August 2011

In this paper we prove that for all pairs

(
d
,
m
)

(d,m)

with

d

/

m
≥
174

/

55

d/m\geq 174/55

, the linear system of plane curves of degree

d
d

with ten general base points of multiplicity

m
m

has the expected dimension.
The use of semiparametric mixed models to analyze PamChip® peptide array data: an application to an oncology experiment
Authors: Thilakarathne Pushpike J. , Clement Lieven , Lin Dan , Shkedy Ziv , Kasim Adetayo , Talloen Willem , Versele Matthias , Verbeke Geert
Published: August 2011

Motivation: Phosphorylation by protein kinases is a central theme in biological systems. Aberrant protein kinase activity has been implicated in a variety of human diseases (e.g. cancer). Therefore, modulation of kinase activity represents an attractive therapeutic approach for the treatment of human illnesses. Thus, identification of signature peptides is crucial for protein kinase targeting and can be achieved by using PamChip® microarray technology. We propose a flexible semiparametric mixed model for analyzing PamChip® data. This approach enables the estimation of the phosphorylation rate (Velocity) as a function of time together with pointwise confidence intervals.

Results: Using a publicly available dataset, we show that our model is capable of adequately fitting the kinase activity profiles and provides velocity estimates over time. Moreover, it allows to test for differences in the velocity of kinase inhibition between responding and non-responding cell lines. This can be done at individual time point as well as for the entire velocity profile.

Contact:  pushpike@med.kuleuven.be

Supplementary information:  Supplementary data are available at Bioinformatics online.