A ternary diophantine inequality by primes with one of the form $\mathbf{p=x^2+y^2+1}$
S. I. Dimitrov
TL;DR
The paper proves the solvability of the ternary Piatetski-Shapiro inequality $|p_1^c+p_2^c+p_3^c-N|<ε$ with primes $p_1$ constrained to the Linnik form $p_1=x^2+y^2+1$ for $1<c<427/400$, by developing a new Bombieri–Vinogradov type bound for exponential sums over primes. The argument combines major/minor arc techniques with an intricate decomposition of the representation numbers $r(p_1-1)$ and a delicate analysis of the resulting exponential sums, including a new upper bound for the trivial arc and a sharp lower bound for the main term. The key components are the asymptotic formula for major-arc contributions, a Bombieri–Vinogradov type estimate for exponential sums over primes, and precise control of auxiliary sums $oldsymbol{Γ_i(X)}$ to show the dominant positive term drives the count to infinity as $X$ grows. This yields solvability for sufficiently large $N$ with the stated form constraint on $p_1$, and it highlights a pathway to further results with multiple special prime forms or broader ranges of $c$.
Abstract
In this paper we solve the ternary Piatetski-Shapiro inequality with prime numbers of a special form. More precisely we show that, for any fixed $1<c<\frac{427}{400}$, every sufficiently large positive number $N$ and a small constant $\varepsilon>0$, the diophantine inequality \begin{equation*} |p_1^c+p_2^c+p_3^c-N|<\varepsilon \end{equation*} has a solution in prime numbers $p_1,\,p_2,\,p_3$, such that $p_1=x^2 + y^2 +1$. For this purpose we establish a new Bombieri -- Vinogradov type result for exponential sums over primes.
