13C99 1 16D80 1 16P40; 16N40 1 16S32 1 16S36 1 16U80 1 16W20 1 16W25 1 2-primal ring 1 2-primal rings 1 central Armendariz rings 1 central reduced rings 1 central reversible rings 1 central semicommutative rings 1 central symmetric rings 1 minimal prime ideal 1 skew PBW extension 1 symmetric rings 1