We construct a Gause-type predator-prey model with concave prey isocline and (at least) two limit cycles. This serves as a counter-example to the global stability criterion of Hsu [Math. Biosci. 39:1-10 (1978)].

We study the behavior of maximal term Dirichlet series with positive exponents sum which is an entire function. For class determined by a convex growth majorant we establish criterion for equivalence logarithms moduli original and modified outside some exceptional set.

In this article we establish the existence of at least two distinct solutions to singular elliptic equations involving a concave term and critical Caffarelli-Kohn-Nirenberg exponent with sign-changing weight functions.

We devise efficient methods for dynamic inverse problems, where both the quantities of interest and forward operator (measurement process) may change in time. Our goal is to solve all simultaneously. consider large-scale ill-posed problems made more challenging by their nature and, possibly, limited amount available data per measurement step. To alleviate these difficulties, we apply a unified ...

We consider a learning algorithm generated by a regularization scheme with a concave regularizer for the purpose of achieving sparsity and good learning rates in a least squares regression setting. The regularization is induced for linear combinations of empirical features, constructed in the literatures of kernel principal component analysis and kernel projection machines, based on kernels and...

We prove that each positive operator from a Banach lattice E to a Banach lattice F with a disjointly strictly singular majorant is itself disjointly strictly singular provided the norm on F is order continuous. We prove as well that if S : E → E is dominated by a disjointly strictly singular operator, then S2 is disjointly strictly singular.

in this paper, under the condition that $k$ is concave, we characterize lacunary series in $q_{k}$ spaces. we improve a result due to h. wulan and k. zhu.

We consider Cournot models of competition, where market participants choose the quantities they demand or supply. We study the loss of aggregate surplus due to the exercise of market power in Cournot competition, for both oligopsony and oligopoly models. We observe that efficiency loss is generally arbitrarily high in Cournot games, but also prove bounds on efficiency loss in several cases of i...

Many real life situations can be described using twice continuously differentiable functions over convex sets with interior points. Such functions have an interesting separation property: At every interior point of the set they separate particular classes of quadratic convex functions from classes of quadratic concave functions. Using this property we introduce new characterizations of the deri...