K491 :
-a^8*x^2*y + 4*a^6*b^2*x^2*y - 6*a^4*b^4*x^2*y + 4*a^2*b^6*x^2*y -   b^8*x^2*y + 2*a^6*c^2*x^2*y - 3*a^4*b^2*c^2*x^2*y + b^6*c^2*x^2*y -   2*a^4*c^4*x^2*y + 2*a^2*c^6*x^2*y + b^2*c^6*x^2*y -   c^8*x^2*y + a^8*x*y^2 - 4*a^6*b^2*x*y^2 + 6*a^4*b^4*x*y^2 -   4*a^2*b^6*x*y^2 + b^8*x*y^2 - a^6*c^2*x*y^2 + 3*a^2*b^4*c^2*x*y^2 -   2*b^6*c^2*x*y^2 + 2*b^4*c^4*x*y^2 - a^2*c^6*x*y^2 -   2*b^2*c^6*x*y^2 + c^8*x*y^2 + a^8*x^2*z - 2*a^6*b^2*x^2*z +   2*a^4*b^4*x^2*z - 2*a^2*b^6*x^2*z + b^8*x^2*z - 4*a^6*c^2*x^2*z +   3*a^4*b^2*c^2*x^2*z - b^6*c^2*x^2*z + 6*a^4*c^4*x^2*z -   4*a^2*c^6*x^2*z - b^2*c^6*x^2*z + c^8*x^2*z - a^8*y^2*z +   2*a^6*b^2*y^2*z - 2*a^4*b^4*y^2*z + 2*a^2*b^6*y^2*z - b^8*y^2*z +   a^6*c^2*y^2*z - 3*a^2*b^4*c^2*y^2*z + 4*b^6*c^2*y^2*z -   6*b^4*c^4*y^2*z + a^2*c^6*y^2*z + 4*b^2*c^6*y^2*z - c^8*y^2*z -   a^8*x*z^2 + a^6*b^2*x*z^2 + a^2*b^6*x*z^2 - b^8*x*z^2 + 4*a^6*c^2*x*z^2 +   2*b^6*c^2*x*z^2 - 6*a^4*c^4*x*z^2 -   3*a^2*b^2*c^4*x*z^2 - 2*b^4*c^4*x*z^2 + 4*a^2*c^6*x*z^2 +   2*b^2*c^6*x*z^2 - c^8*x*z^2 + a^8*y*z^2 - a^6*b^2*y*z^2 - a^2*b^6*y*z^2 +   b^8*y*z^2 - 2*a^6*c^2*y*z^2 - 4*b^6*c^2*y*z^2 +   2*a^4*c^4*y*z^2 + 3*a^2*b^2*c^4*y*z^2 + 6*b^4*c^4*y*z^2 -   2*a^2*c^6*y*z^2 - 4*b^2*c^6*y*z^2 + c^8*y*z^2 = 0