Let s ? 3 $s \geqslant 3$ be a natural number, let ? ( x ) $\psi (x)$ polynomial with real coefficients and degree d 2 $d 2$ , A $A$ some large, non-empty, finite subset of numbers. We use E $E_{s,2}(A)$ to denote the number solutions system equations ? i = 1 ? + 0 \begin{equation*}\hskip2.5pc \sum _{i=1}^{s} (\psi (x_i) - \psi (x_{i+s}) )= (x_i x_{i+s} 0, \end{equation*} where ? $x_i \in A$ fo...

Abstract When $k\geqslant 4$ and $0\leqslant d\leqslant (k-2)/4$ , we consider the system of Diophantine equations \begin{align*}x_1^j+\ldots +x_k^j=y_1^j+\ldots +y_k^j\quad (1\leqslant j\leqslant k,\, j\ne k-d).\end{align*} We show that in this cousin a Vinogradov system, there is paucity non-diagonal positive integral solutions. Our quantitative estimates are particularly sharp when $d=o\!\le...

Given a family $$\varphi = (\varphi_1, \ldots, \varphi_d)\in \mathbb{Z}[T]^d$$ of d distinct nonconstant polynomials, positive integer $$k\le d$$ and real parameter $$\rho$$ , we consider the mean value $$M_{k, \rho} (\varphi, N) \int_{{\rm x} \in [0,1]^k} \sup_{{\rm y} [0,1]^{d-k}} | S_{\varphi}({\rm x}, {\rm y}; |^\rho \,d{\rm $$ of exponential sums $$S_{\varphi}({\rm \sum_{n=1}^{N} \...