I have 10 binary variables $x_0, ..,,x_4$ and $y_0,..,y_4$. I know $y_i=x_i+x_{(i+1)\bmod 5}$. I want to write $x_i$ in terms of $y$ variables. I know for this toy case we can use Gaussian elimination. But in actual case $y_i$s are nonlinear equations. I tried this idea:
n = 5
RING = PolynomialRing(GF(2),2*n,['x%d'%(i) for i in range(n)] + ['y%d'%(i) for i in range(n)])
RING.inject_variables()
Z = list(RING.gens())
E=[y0==x0+x1, y1==x1+x2, y2==x2+x3, y3==x3+x4, y4==x4+x0]
solve(E, x0,x1,x2,x3,x4)
It is not working.