groebner基计算时，含有a1，a2,a3,...,an个自变量的非线性方程组问题化简问题

lhrman

a1*a2+2*a1*a3+a2*a3=0
a1^2+a1*a2+a2^2+a2*a3+a3^2=1/4;
a1+a2+a3=1
9 E) h, r* j8 o; N/ A# R: R用with（Groebner）；
然后输入
- o3 w% h3 I% Z; `x := seq(a[k], k = 0 .. n)
" x/ e* V$ L- s. D Basis(pl1, plex(x));
%;
: z6 E9 r* N% ~& y0 ]& oError, too many levels of recursion
Basis(pl1, prod(x));
%;
, }: F# \, b& O% F3 e8 {Error, too many levels of recursion
然后显示错误求高手指点，我做的东西最好用a1,a2,...,an这样设置未知数我好编程