Title: The quadratic Waring-Goldbach problem
Author: Jianya Liu, Tao Zhan
Abstract: The purpose of this paper is to briefly survey recent progress towards the quadratic Waring-Goldbach problem. Contents of the paper are as follows: the Waring-Goldbach problem, the circle method, Hua's theorem with five almost equal prime variables, treatment of the enlarged major arcs, the major arcs in the representation by four squares of primes, mean-value etimates for Dirichlet polynomials, the minor arcs and exceptional set in the representation by four squares of primes, estimates of exponential sums over primes, sieve methods in the representation by four squares of primes, Lagrange's theorem with almost prime variables, the Linnik-Gallagher problem, new results for Hua's theorem with five almost equal prime variables, sums of three squares of almost primes, Sarnak's conjecture and ternary quadratic forms.
Attachment: The quadratic Waring-Goldbach problem