K567 :
a^2*c^2*x^2*y - b^2*c^2*x^2*y - a^2*c^2*x*y^2 + b^2*c^2*x*y^2 +   a^2*b^2*x^2*z - b^2*c^2*x^2*z + 2*a^4*x*y*z - 2*a^2*b^2*x*y*z +   2*b^4*x*y*z - 2*a^2*c^2*x*y*z - 2*b^2*c^2*x*y*z +   2*c^4*x*y*z + a^2*b^2*y^2*z - a^2*c^2*y^2*z - a^2*b^2*x*z^2 +   b^2*c^2*x*z^2 - a^2*b^2*y*z^2 + a^2*c^2*y*z^2 = 0