pp 245-247 August 2011
On Diophantine Equations of the Form $(x-a_1)(x-a_2)\ldots(x-a_k)+r=y^n$
Erdős and Selfridge [3] proved that a product of consecutive integers can never be a perfect power. That is, the equation $x(x+1)(x+2)\ldots(x+(m-1))=y^n$ has no solutions in positive integers $x,m,n$ where $m,n>1$ and $y\in Q$. We consider the equation
$$(x-a_1)(x-a_2)\ldots(x-a_k)+r=y^n$$
where $0\leq a_1 < a_2 <\cdots < a_k$ are integers and, with $r\in Q,n\geq 3$ and we prove a finiteness theorem for the number of solutions 𝑥 in $Z,y$ in 𝑄. Following that, we show that, more interestingly, for every nonzero integer $n>2$ and for any nonzero integer 𝑟 which is not a perfect 𝑛-th power for which the equation admits solutions, 𝑘 is bounded by an effective bound.
pp 249-257 August 2011
A Classification of Cubic Symmetric Graphs of Order $16p^2$
Mehdi Alaeiyan B N Onagh M K Hosseinipoor
A graph is called symmetric if its automorphism group acts transitively on its arc set. In this paper, we classify all connected cubic symmetric graphs of order $16p^2$ for each prime 𝑝.
pp 259-265 August 2011
Deficiently Extremal Gorenstein Algebras
The aim of this article is to study the homological properties of deficiently extremal Gorenstein algebras. We prove that if $R/I$ is an odd deficiently extremal Gorenstein algebra with pure minimal free resolution, then the codimension of $R/I$ must be odd. As an application, the structure of pure minimal free resolution of a nearly extremal Gorenstein algebra is obtained.
pp 267-290 August 2011
Existence of Dicritical Divisors Revisited
Shreeram S Abhyankar William J Heinzer
We characterize the dicriticals of special pencils. We also initiate higher dimensional dicritical theory.
pp 291-300 August 2011
Test Rank of an Abelian Product of a Free Lie Algebra and a Free Abelian Lie Algebra
Naime Ekici Nazar Şahin Öğüşlü
Let 𝐹 be a free Lie algebra of rank $n\geq 2$ and 𝐴 be a free abelian Lie algebra of rank $m\geq 2$. We prove that the test rank of the abelian product $F\times A$ is 𝑚. Morever we compute the test rank of the algebra $F/\gamma k(F)'$.
pp 301-310 August 2011
Uniqueness and Zeros of 𝑞-Shift Difference Polynomials
Kai Liu Xin-Ling Liu Ting-Bin Cao
In this paper, we consider the zero distributions of 𝑞-shift difference polynomials of meromorphic functions with zero order, and obtain two theorems that extend the classical Hayman results on the zeros of differential polynomials to 𝑞-shift difference polynomials. We also investigate the uniqueness problem of 𝑞-shift difference polynomials that share a common value.
pp 311-325 August 2011
Spherical Means in Annular Regions in the 𝑛-Dimensional Real Hyperbolic Spaces
Let $Z_{r,R}$ be the class of all continuous functions 𝑓 on the annulus $\mathrm{Ann}(r,R)$ in the real hyperbolic space $\mathbb{B}^n$ with spherical means $M_sf(x)=0$, whenever $s>0$ and $x\in\mathbb{B}^n$ are such that the sphere $S_s(x)\subset\mathrm{Ann}(r,R)$ and $B_r(o)\subseteq B_s(x)$. In this article, we give a characterization for functions in $Z_{r,R}$. In the case $R=\infty$, this result gives a new proof of Helgason’s support theorem for spherical means in the real hyperbolic spaces.
pp 327-337 August 2011
Composition Operators between Bloch Type Spaces and Zygmund Spaces in the Unit Ball
The boundedness and compactness of composition operators between Bloch type spaces and Zygmund spaces of holomorphic functions in the unit ball are characterized in the paper.
pp 339-348 August 2011
Existence of Solution of the Pullback Equation Involving Volume Forms
Let $\Omega\subset\mathbb{R}^n$ be a smooth, bounded domain. We study the existence and regularity of diffeomorphisms of 𝛺 satisfying the volume form equation
$$\phi^\ast(g)=f,\quad\text{in}\, \Omega$$
where $f,g\in C^{m,\alpha}(\overline{\Omega};\Lambda^n)$ are given positive volume forms.
pp 349-367 August 2011
Value Functions for Certain Class of Hamilton Jacobi Equations
Anup Biswas Rajib Dutta Prosenjit Roy
We consider a class of Hamilton Jacobi equations (in short, HJE) of type
$$u_t+\frac{1}{2}\left(|u_{x_n}|^2+\cdots+|u_{x_{n-1}}|^2\right)+\frac{e^u}{m}|u_{x_n}|^m=0,$$
in $\mathbb{R}^n\times\mathbb{R}_+$ and $m>1$, with bounded, Lipschitz continuous initial data. We give a Hopf-Lax type representation for the value function and also characterize the set of minimizing paths. It is shown that the minimizing paths in the representation of value function need not be straight lines. Then we consider HJE with Hamiltonian decreasing in 𝑢 of type
$$u_t+H_1(u_{x_1},\ldots,u_{x_i})+e^{-u}H_2(u_{x_{i+1}},\ldots,u_{x_n})=0$$
where $H_1,H_2$ are convex, homogeneous of degree $n,m>1$ respectively and the initial data is bounded, Lipschitz continuous. We prove that there exists a unique viscosity solution for this HJE in Lipschitz continuous class. We also give a representation formula for the value function.
pp 369-377 August 2011
An almost Sure Central Limit Theorem for the Weight Function Sequences of NA Random Variables
Consider the weight function sequences of NA random variables. This paper proves that the almost sure central limit theorem holds for the weight function sequences of NA random variables. Our results generalize and improve those on the almost sure central limit theorem previously obtained from the i.i.d. case to NA sequences.
Current Issue
Volume 129 | Issue 3
June 2019
© 2017-2019 Indian Academy of Sciences, Bengaluru.