Groups acting simply transitively on the vertices of a building of typeà 2, I

If a group acts simply transitively on the vertices of an affine building with connected diagram, then must be of typeà _n–1 for somen2, and must have a presentation of a simple type. The casen=2, when is a tree, has been studied in detail. We consider the casen=3, motivated particularly by the case when is the building ofG=PGL(3,K),K a local field, and when G. We exhibit such a group whenK=F _q ((X)),q any prime power. Our study leads to combinatorial objects which we calltriangle presentations. These triangle presentations give rise to some new buildings of typeà ₂.     

Correction to: ‘The UCT, the Milnor Sequence, and a Canonical Decomposition of the Kasparov Groups’

In this note we correct a mistake in K-Theory 10 (1996), 49–72. In that paper we asserted that under bootstrap hypotheses the short exact sequence

Addendum to “The Structure of Groups of Order 2^3p^2

Tbe present paper is a complement to the paper [1]. It is proved that groups of order 2^37^2 have 44 types.     

The Einstein-Kahler metrics on Cartan-Hartogs domain of the first type

Let YI be the Cartan-Hartogs domain of the first type. We give the generating function of the Einstein-Kahler metrics on YI, the holomorphic sectional curvature of the invariant Einstein-Kahler metrics on YI. The comparison theorem of complete Einstein-Kahler metric and Kobayashi metric on YI is provided for some cases. For the non-homogeneous domain YI, when K =mn+1/m+n,m>1, the explicit forms of the complete Einstein-Kahler metrics are obtained.     

The impact of Allee effect on a predator–prey system with Holling type II functional response

In this paper, the Allee effect is incorporated into a predator–prey model with Holling type II functional response. Compared with the predator–prey model without Allee effect, we find that the Allee effect of prey species increases the extinction risk of both predators and prey. When the handling time of predators is relatively short and the Allee effect of prey species becomes strong, both predators and prey may become extinct. Moreover, it is shown that the model with Allee effect undergoes the Hopf bifurcation and heteroclinic bifurcation. The Allee effect of prey species can lead to unstable periodical oscillation. It is also found that the positive equilibrium of the model could change from stable to unstable, and then to stable when the strength of Allee effect or the handling time of predators increases continuously from zero, that is, the model admits stability switches as a parameter changes. When the Allee effect of prey species becomes strong, longer handling time of predators may stabilize the coexistent steady state.     

The Characterizations of Weighted H^p（w）Spaces on the Certain Groups

ＴｈｅＣｈａｒａｃｔｅｒｉｚａｔｉｏｎｓｏｆＷｅｉｇｈｔｅｄ　Ｈ~ｐ（ｗ）ＳｐａｃｅｓｏｎｔｈｅＣｅｒｔａｉｎＧｒｏｕｐｓＺｏｕＪｉｎ（邹进）（Ｌｅｓｈａｎ，ＴｈｅａｃｈｅｒｓＣｏｌｌｅｇｅ，Ｃｈｉｎａ）Ａｂｓｔｒａｃｔ：ＴｈｅｗｅｉｇｈｔｅｄＨＰ（?..     

Cohomology of osp(2|2) acting on spaces of linear differential operators on the superspace ℝ1|2

We compute the first differential cohomology of the orthosymplectic Lie superalgebra osp(2|2) with coefficients in the superspace of linear differential operators acting on the space of weighted densities on the (1, 2)-dimensional real superspace. We also compute the same, but osp(1|2)-relative, cohomology. We explicitly give 1-cocycles spanning these cohomologies. This work is the simplest generalization of a result from [1].     

The Einstein-Kähler metric on Hua construction of the first type

Let HC_I be the Hua construction of the first type. We describe the Einstein-Kähler metric for HC_I. We reduce the Monge-Ampè re equation for the metric to an ordinary differential equation in the auxiliary function\(X\left( {z,w,\zeta } \right)\) This differential equation can be solved to give an implicit function in\(X\left( {z,w,\zeta } \right)\). For some cases, we obtained the solution of the differential equation and the explicit forms of the complete Einstein-Kähler metrics on HC_I which are the non-homogeneous domains.     

Local structure of graphs with λ=μ=2,a 2=4

Several properties of graphs with ==2,a ₂=4 are studied. It is proved that such graphs are locally unions of triangles, hexagons or heptagons. As a consequence, a distance regular graph with intersection array (13,10,7;1,2,7) does not exist.     

The Einstein-Khler metric on Hua construction of the first type

Let HCI be the Hua construction of the first type. We describe the Einstein-Kahler metric for HCI. We reduce the Monge-Ampere equation for the metric to an ordinary differential equation in the auxiliary function X(z,w,ζ). This differential equation can be solved to give an implicit function in x(z,w,ζ). For some cases, we obtained the solution of the differential equation and the explicit forms of the complete Einstein-Kahler metrics on HCI which are the non-homogeneous domains.     

A technique for calculating the γ-matrix structures of the diagrams of a total four-fermion interaction with infinite number of vertices ind=2+ε dimensional regularization

It is known [1] that ind=2+ dimensional regularization any four-fermion interaction generates an infinite number of counterterms of the form     

The method of infinite ascent applied on A 4 ± nB 3 = C 2

Each of the Diophantine equations A ⁴ ± nB ³ = C ² has an infinite number of integral solutions (A,B,C) for any positive integer n. In this paper, we will show how the method of infinite ascent could be applied to generate these solutions. We will investigate the conditions when A, B and C are pair-wise co-prime. As a side result of this investigation, we will show a method of generating an infinite number of co-prime integral solutions (A,B,C) of the Diophantine equation aA ³ +cB ³ = C ² for any co-prime integer pair (a, c).     

The structure of the 2-Sylow subgroup of K2(?), II

The 2-Sylow subgroup of the tame kernel K ₂() of a totally real number field E is described in terms of twisted class groups and the cohomology of unit groups of 2-power cyclotomic extensions of E.     

On a transformation of the wiener process in ℝ m by a functional of the local time type on a surface

A transformation of the Wiener process _t in ^m is considered. This transformation is realized by a multiplicative functional _l=u(_l/u(₀), where the functionu is constructed in a certain way by using a functional of the local time type on a surface. It is proved that this transformation is equivalent to the successive application of an absolutely continuous change of a measure and killing on the surface.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 45, No. 6, pp. 863–866, June, 1993.     

Spectral Theory for a Mathematical Model of the Weak Interaction: The Decay of the Intermediate Vector Bosons W ��, II

We do the spectral analysis of the Hamiltonian for the weak leptonic decay of the gauge bosons W ^±. Using Mourre theory, it is shown that the spectrum between the unique ground state and the first threshold is purely absolutely continuous. Neither sharp neutrino high-energy cutoff nor infrared regularization is assumed.     

On the nonexistence of nontrivial perfecte-codes and tight 2e-designs in hamming schemesH(n,q) withe ≥ 3 andq ≥ 3

It is known that if there exist perfecte-codes or tight 2e-designs in a Hamming schemeH(n, q), then all the zeros of the Lloyd polynomial $$F_e \left( x \right) = \sum\limits_{i = 0}^e {\left( { - q} \right)^i \left( {q - 1} \right)^{e - i} } \left( {\begin{array}{*{20}c} {n - i - 1} \\ {e - i} \\ \end{array} } \right)\left( {\begin{array}{*{20}c} {x - 1} \\ i \\ \end{array} } \right)$$ are integers in the interval [1,n]. With some results of Best, we show that ife ≥ 3,n ≥ e + 1, andq ≥ 3, thenF _e (x) has a nonintegral zero. Therefore there exist no nontrivial perfecte-codes and tight 2e-designs inH(n,q) ife ≥ 3 andq ≥ 3.