Semisemiological structure of the prime numbers and conditional Goldbach theorems.
We show that if A and B are subsets of the primes with positive relative lower densities α and β, then the lower density of A+B in the natural numbers is at least , which is asymptotically best possible. This improves results of Ramaré and Ruzsa and of Chipeniuk and Hamel. As in the latter work, the problem is reduced to a similar problem for subsets of using techniques of Green and Green-Tao. Concerning this new problem we show that, for any square-free m and any of densities α and β, the...