13C99 16D80 3 16U80 2 $J$-symmetric ring 1 13C13 1 2-primal rings 1 Jacobson radical 1 Noetherian space 1 Rickart modules 1 Spectral space 1 abelian modules 1 central Armendariz rings 1 central reduced rings 1 central reversible rings 1 central semicommutative rings 1 central symmetric rings 1 irreducible space 1 principally projective modules 1 reduced modules 1 rigid modules 1 semicommutative modules 1 symmetric modules 1 symmetric ring 1 symmetric rings 1 top modules 1