The present algebraic development begins by an exposition of the data of the problem. The definition of the primal radius r>0 is : For all positive integer x≥3 exists a finite number of integers called the primal radius r>0, for which x+r and x-r are prime numbers. The corollary is that 2x=(x+r)+(x-r) is always the sum of a finite number of primes. Also, for all positive integer x≥0, exists an infinity of integers r>0, for which x+r and r-x are prime numbers. The conclusion is that 2x=(x+r)-(r-x) is always an infinity of differences of primes.
Bulletin of Mathematical Sciences and Applications (Volume 5)
J. Ghanouchi "About an even as the Sum or the Difference of Two Primes", Bulletin of Mathematical Sciences and Applications, Vol. 5, pp. 35-43, 2013