Let $H_0$ be a discrete periodic Schr\"odinger operator on $\ell^2(\mathbb{Z}^d)$: $$H_0=-\Delta+V,$$ where $\Delta$ is the Laplacian and $V: \mathbb{Z}^d\to \mathbb{C}$ periodic. We prove that for any $d\geq3$, Fermi variety at every energy level irreducible (modulo periodicity). For $d=2$, we except average of potential periodicity) has most two components This sharp since $d=2$ constant $V$,...

For ε ≠ 0 sufficiently small we provide sufficient conditions for the existence of periodic solutions for the Lienard differential equations of the form x'' + f ⁢(x)⁢ x' + n2⁢x + g (x) = ε2p1 ⁢(t) + ε3 ⁢p2(t), where n is a positive integer, f : ℝ → ℝ is a C 3 function, g : ℝ → ℝ is a C 4 function, and p i : ℝ → ℝ for i = 1, 2 are continuous 2π-periodic function. The main tool used in this paper...

Periodic environments may either enhance or suppress a population via resonant or attenuant cycles. We derive signature functions for predicting the responses of two competing populations to 2-periodic oscillations in six model parameters. Two of these parameters provide a non-trivial equilibrium and two provide the carrying capacities of each species in the absence of the other, but the remain...

We study the existence of periodic solutions of the non–autonomous periodic Lyness’ recurrence un+2 = (an +un+1)/un, where {an}n is a cycle with positive values a,b and with positive initial conditions. It is known that for a = b = 1 all the sequences generated by this recurrence are 5–periodic. We prove that for each pair (a, b) 6= (1, 1) there are infinitely many initial conditions giving ris...

Populations are either enhanced via resonant cycles or suppressed via attenuant cycles by periodic environments. We develop a signature function for predicting the response of discretely reproducing populations to 2-periodic fluctuations of both a characteristic of the environment (carrying capacity), and a characteristic of the population (inherent growth rate). Our signature function is the s...

We study approximation by arbitrary linear combinations of $n$ translates a single function periodic functions. construct some methods this for univariate functions in the class induced convolution with function, and prove upper bounds $L^p$-approximation convergence rate these methods, when $n \to \infty$, $1 \leq p \infty$. also generalize results to classes multivariate defined tensor produc...

and Applied Analysis 3 where α > 0, λ > 0, and p > 1. Their proof revealed that if the initial data is small enough, then there exists a unique solution. Once removing the assumption that the initial data is small, then one should addN ≤ 4 with p > 1 orN ≥ 5 with 1 < p ≤ N/ N−4 to assure the existence of a unique solution. Further, from their results, one can also find that the solutions of 1.5...