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1.
2.
We present results on total domination in a partitioned graph G = (V, E). Let γ
t
(G) denote the total dominating number of G. For a partition , k ≥ 2, of V, let γ
t
(G; V
i
) be the cardinality of a smallest subset of V such that every vertex of V
i
has a neighbour in it and define the following
We summarize known bounds on γ
t
(G) and for graphs with all degrees at least δ we derive the following bounds for f
t
(G; k) and g
t
(G; k).
相似文献
| (i) | For δ ≥ 2 and k ≥ 3 we prove f t (G; k) ≤ 11|V|/7 and this inequality is best possible. |
| (ii) | for δ ≥ 3 we prove that f t (G; 2) ≤ (5/4 − 1/372)|V|. That inequality may not be best possible, but we conjecture that f t (G; 2) ≤ 7|V|/6 is. |
| (iii) | for δ ≥ 3 we prove f t (G; k) ≤ 3|V|/2 and this inequality is best possible. |
| (iv) | for δ ≥ 3 the inequality g t (G; k) ≤ 3|V|/4 holds and is best possible. |
3.
Here we prove the following result.
Theorem 1.1.Let X be an integral projective curve of arithmetic genus g and k≧ ≧4 an integer. Assume the existence of L ∈ Pick
(X) with h
0
(X, L)=2 and L spanned. Fix a rank 1 torsion free sheaf M on X with h
0(X,M)=r+1≧2, h1
(X, M)≧2 and M spanned by its global sections. Set d≔deg(M) and s≔max {n≧0:h
0 (X, M ⊗(L*)⊗n)>0}. Then one of the following cases occur:
We find also other upper bounds onh
0 (X, F).
| (a) | M≊L ⊗r; |
| (b) | M is the subsheaf of ω X⊗(L*)⊗t, t:=g−d+r−1, spanned by H0(X, ωX⊗(L*)⊗t); |
| (c) | there is a rank 1 torsion free sheaf F on X with 1≦h 0(X, F)≦k−2 such that M≊L⊗s⊗F. Moreover, if we fix an integer m with 2≦m≦k−2 and assume r#(s+1)k−(ns+n+1) per every 2≦n≦m, we have h0 (X, F)≦k−m−1. |
Sunto In questo lavoro si dimostra il seguente teorema. Teorem 1.1.Sia X una curva proiettiva ridotta e irriducibile di genere aritmetico g e k≥4 un intero. Si supponga l'esistenza di L ε Pick (X) con h 0 (X, L)=2 e L generato. Si fissi un fascio senza torsione di rango uno M su X con h0 (X, M)=r++1≥2, h1 (X, M) ≧2 e M generato dalle sue sezioni globali. Si ponga d≔deg(M) e s≔max{n≧0:h 0(X, M ⊗(L*)⊗n)>0}. Allora si verifica uno dei casi seguenti:相似文献Si ricavano anche altre maggiorazioni suh 0,(X, F).
(a) M≊L ⊗r; (b) M è il sottofascio di ω X⊗(L*)⊗t, t:=g−d+r−1 generato da H0 (X, ωX⊗(L*)⊗t); (c) esiste un fascio senza torsione di rango un F su X con 1≦h 0 (X, F) <=k−2 tale che M ≊L ⊗8 ⊗ F. Inoltre, se si fissa un intero m con 2≦m≦k−2 e si suppone r#(s+1) k−(ns+n+1) per ogni 2≦n≦m, si ottiene h 0 (X, F)≦k−m−1.
4.
Laurent Bartholdi 《Israel Journal of Mathematics》2006,154(1):93-139
We develop the theory of “branch algebras”, which are infinite-dimensional associative algebras that are isomorphic, up to
taking subrings of finite codimension, to a matrix ring over themselves. The main examples come from groups acting on trees.
In particular, for every field
% MathType!End!2!1! we contruct a
% MathType!End!2!1! which
The author acknowledges support from TU Graz and UC Berkeley, where part of this research was conducted. 相似文献
| – | • is finitely generated and infinite-dimensional, but has only finitedimensional quotients; |
| – | • has a subalgebra of finite codimension, isomorphic toM 2(k); |
| – | • is prime; |
| – | • has quadratic growth, and therefore Gelfand-Kirillov dimension 2; |
| – | • is recursively presented; |
| – | • satisfies no identity; |
| – | • contains a transcendental, invertible element; |
| – | • is semiprimitive if % MathType!End!2!1! has characteristic ≠2; |
| – | • is graded if % MathType!End!2!1! has characteristic 2; |
| – | • is primitive if % MathType!End!2!1! is a non-algebraic extension of % MathType!End!2!1!; |
| – | • is graded nil and Jacobson radical if % MathType!End!2!1! is an algebraic extension of % MathType!End!2!1!. |
5.
Giuseppe Pellegrino 《Rendiconti del Circolo Matematico di Palermo》1998,47(1):141-168
| 1. | Letm be the greatest integer such that . ThenPG(3,q) contains complete caps of sizek=(m+1)(q+1)+ω, with ω=0, 1, 2. | |
| 2. |
PG(3,q),q≥5, contains complete caps of size |
|
| 3. | InPG(3,q) complete caps different from ovaloids have some external planes. |
6.
Yuji Kobayashi 《Archiv der Mathematik》2005,85(3):227-232
Let k ≧ 3 be an integer or k = ∞ and let K be a field. There is a recursive family
of finitely presented groups Gn over a fixed finite alphabet with solvable word problem such that
Received: 22 July 2004 相似文献
| (1) | the center of Gn is trivial for every |
| (2) | the dimension d(n) of the center of the group algebra K · Gn over K is either 1 or k, and |
| (3) | it is undecidable given n whether d(n) = 1 or d(n) = k. |
7.
Stevo Stević 《Mediterranean Journal of Mathematics》2008,5(1):61-76
In this paper we investigate harmonic Hardy-Orlicz and Bergman-Orlicz b
φ,α
(B) spaces, using an identity of Hardy-Stein type. We also extend the notion of the Lusin property by introducing (φ, α)-Lusin property with respect to a Stoltz domain. The main result in the paper is as follows: Let be a nonnegative increasing convex function twice differentiable on (0, ∞), and u a harmonic function on the unit ball B in . Then the following statements are equivalent:
相似文献
| (a) | . |
| (b) | . |
| (c) | u has (φ, α)-Lusin property with respect to a Stoltz domain with half-angle β, for any . |
| (d) | u has (φ, α)-Lusin property with respect to a Stoltz domain with half-angle β, for some . |
8.
Eric Schmutz 《Central European Journal of Mathematics》2008,6(3):482-487
It is known that the unit sphere, centered at the origin in ℝ
n
, has a dense set of points with rational coordinates. We give an elementary proof of this fact that includes explicit bounds
on the complexity of the coordinates: for every point ν on the unit sphere in ℝ
n
, and every ν > 0; there is a point r = (r
1; r
2;…;r
n) such that:
One consequence of this result is a relatively simple and quantitative proof of the fact that the rational orthogonal group
O(n;ℚ) is dense in O(n;ℝ) with the topology induced by Frobenius’ matrix norm. Unitary matrices in U(n;ℂ) can likewise be approximated by matrices in U(n;ℚ(i))
相似文献
| – | ⊎ ‖r-v‖∞ < ε. |
| – | ⊎ r is also a point on the unit sphere; Σ r i 2 = 1. |
| – | ⊎ r has rational coordinates; for some integers a i , b i . |
| – | ⊎ for all . |
9.
Let G be a 2-edge-connected simple graph with girth g, independence number α(G), and if one of the following two conditions holds
then G is upper embeddable and the lower bound v − 3g + 7 is best possible. Similarly the result for 3-edge-connected simple graph with girth g and independence number α(G) is also obtained.
Huang Yuanqiu: Partially supported by National Science Foundation of China (No. 10771062) and Program for New Century Excellent
Talents in University (No. NCET-07-0276). 相似文献
| (1) | α(G) ≤ 2; | |
| (2) | α(G) ≥ 3, and for any three nonadjacent vertices v
i
(i = 1,2,3), it has
|
10.
11.
A. I. Pavlov 《Mathematical Notes》2000,68(3):370-377
The main result of this paper is the following theorem. Suppose thatτ(n) = ∑
d|n
l and the arithmetical functionF satisfies the following conditions:
Then there exist constantsA
1,A
2, andA
3 such that for any fixed \g3\s>0 the following relation holds:
. Moreover, if for any primep the inequality \vbf(p)\vb\s<1 holds and the functionF is strongly multiplicative, thenA
1\s>0.
Translated fromMatematicheskie Zametki, Vol. 68, No. 3, pp. 429–438, September, 2000. 相似文献
| 1) | the functionF is multiplicative; |
| 2) | ifF(n) = ∑ d|n f(d), then there exists an α>0 such that the relationf(n)=O(n −α) holds asn→∞. |
12.
Alessandro Verra 《manuscripta mathematica》1988,62(4):417-435
Let SG(1,3)p5 be a smooth, irreducible, non degenerate surface in the complex grassmannian G(1,3). Assume deg(S)=9, we show that S is one of the following surfaces:
相似文献
| (a) | A K3 surface blown up in one point. |
| (b) | The image of P2 by the linear system |
| (c) | The image of P2 by the linear system . |
13.
Abstract This paper develops the model theory of ordered structures that satisfy Keisler’s regularity scheme and its strengthening REF
(the reflection scheme) which is an analogue of the reflection principle of Zermelo-Fraenkel set theory. Here is a language with a distinguished linear order <, and REF
consists of formulas of the form
where φ is an -formula, φ
<x
is the -formula obtained by restricting all the quantifiers of φ to the initial segment determined by x, and x is a variable that does not appear in φ. Our results include:
Theorem
The following five conditions are equivalent for a complete first order theory T in a countable language
with a distinguished linear order:
Moreover, if κ is a regular cardinal satisfying κ = κ
<κ
, then each of the above conditions is equivalent to:
相似文献
| (1) | Some model of T has an elementary end extension with a first new element. |
| (2) | T ⊢ REF . |
| (3) | T has an ω 1-like model that continuously embeds ω 1. |
| (4) | For some regular uncountable cardinal κ, T has a κ-like model that continuously embeds a stationary subset of κ. |
| (5) | For some regular uncountable cardinal κ, T has a κ-like model that has an elementary extension in which the supremum of M exists. |
| (6) | T has a κ + -like model that continuously embeds a stationary subset of κ. |
14.
E. G. Kwon 《Integral Equations and Operator Theory》2009,64(2):251-260
We characterize the composition operators mapping Blochs boundedly into the weighted Bergman spaces of logarithmic weight.
For 0 < p < ∞, 1 < α < ∞, let Ap, log α denote the space of holomorphic functions F in the unit disc D for which
and let Ap, log ασ denote the class of holomorphic self maps f of D for which
Then for the Bloch pullback operator Cf, the following are equivalent:
This work was supported by the Korea Research Foundation Grant funded by the Korean Government (MOEHRD, Basic Research Promotion
Fund) (KRF-2007-313-C00026). 相似文献
| (1) | Cf maps Bloch space boundedly into A2p, log α |
| (2) | |
| (3) | . |
15.
Yōhei Yamasaki 《Graphs and Combinatorics》1989,5(1):275-282
We have generalized the theory of Shannon's games in [10]. In this paper, we treat a game on a graph with an action of elementary abelian group but our decision of the winner is more general. Our theory can be applied for non-negative integersn andr, to the two games on a graph withn + 1 distinguished terminals whose rules are as follows:
Dedicated to Professor Sin Hitotumatu for his 60'th birthday 相似文献
| (1) | the players Short and Cut play alternately to choose an edge, |
| (2) | the former contracts it and the later deletes it |
| (3) | the former if and only if he connects the terminals into at mostn – r + 1 ones. |
16.
Let X be a Banach space and let (ξj)j ≧ 1 be an i.i.d. sequence of symmetric random variables with finite moments of all orders. We prove that the following assertions
are equivalent:
Received: 10 January 2005; revised: 5 April 2005 相似文献
| 1. |
There exists a constant K such that
|
|
| 2. | X is isomorphic to a Hilbert space. |
17.
Birge Zimmermann Huisgen 《manuscripta mathematica》1991,70(1):157-182
We show that all projective resolutions over a monomial relations algebra Λ simplify drastically at the stage of the second
syzygy; more precisely, we show that the kernel of any homomorphism between two projective left Λ-modules is isomorphic to
a direct sum of principal left ideals generated by paths. As consequences, we obtain:
This research was partially supported by a grant from the National Science Foundation. 相似文献
| (a) | a tight approximation of the finitistic dimensions of Λ in terms of the (very accessible) projective dimensions of the principal left ideals generated by paths; |
| (b) | a basis for comparison of the ‘big’ and ‘little’ finitistic dimensions of Λ, yielding in particular that these two invariants cannot differ by more than 1 and that they are equal in ‘most’ cases; |
| (c) | manageable algorithms for computation of finitistic dimensions. |
18.
19.
Gaston Casanova 《Advances in Applied Clifford Algebras》2005,15(1):151-155
All the letters represent relative integers, except
and
and i = e1e2 in R(2, 0) oder e1 in R(1, 0).
We study the Fermat’s equation
a, b, c being prime two and two and by utilizing an elementary method. We use the Gauss’ formula
where n = 5, 7, 11, 17.
相似文献
| (1) |
| 1. |
If 2 is the p · g · c · d· of A and B we put
|
||
| 2. |
If βn = bn / (c − a) is not divisible by n, we write the expansion
|
||
| 3. | If one a, b oder c is divisible by n we prove the impossibility | ||
| 4. | In the case n = 3 the ring {a + bj} is euclidian which permits to conclude in favour of the impossibility. |
20.
Asher M. Kach 《Archive for Mathematical Logic》2008,47(3):211-219
The main result is that for sets , the following are equivalent:
Other results discuss the relationship between these sets and the sets.
The author’s research was partially supported by a VIGRE grant fellowship. The author thanks Denis Hirschfeldt and Steffen
Lempp for an insightful conversation about LIMINF sets; Christopher Alfeld and Robert Owen for numerous comments and suggestions; and his thesis advisor Steffen Lempp for
his guidance. 相似文献
| (1) | The shuffle sum σ(S) is computable. |
| (2) | The set S is a limit infimum set, i.e., there is a total computable function g(x, t) such that enumerates S. |
| (3) | The set S is a limitwise monotonic set relative to 0′, i.e., there is a total 0′-computable function satisfying such that enumerates S. |