该文定义了环R=F2+uF2+u^2F2+u^3F2的F2^4的一个新的Gray映射,其中u^4=0。证明了R上长为n的(1+u+u2+u3)-循环码的Gray象是F2上长为4n的距离不变的线性循环码。进一步确定了R上奇长度的该常循环码的Gray象的生成多项式,并得到了一些最优的二元线性循环码。
A new Gray map is defined from R =- F2 + uF2 + u2F2 + u3F2 to F2^4 with u4 = 0. It is proved that the Gray image of a linear (1 + u + u2 + u3) -cyclic code of length n over R is a distance-invariant linear cyclic code of length 4n over F2. Further more, the generator polynomials of the Gray image of this constacyclic code for odd length over R is determined, some optimal binary linear cyclic codes are also obtained.