LIB "deform.lib"; ring R=32003,(x,y,z),ds; //---------------------------------------------------- // hypersurface case (from series T[p,q,r]): int p,q,r = 3,3,4; poly f = x^p+y^q+z^r+xyz; print(deform(f)); // the miniversal deformation of f=0 is the projection from the // miniversal total space to the miniversal base space: // { (A,B,C,D,E,F,G,H,x,y,z) | x3+y3+xyz+z4+A+Bx+Cxz+Dy+Eyz+Fz+Gz2+Hz3 =0 } // --> { (A,B,C,D,E,F,G,H) } //---------------------------------------------------- // complete intersection case (from series P[k,l]): int k,l =3,2; ideal j=xy,x^k+y^l+z2; print(deform(j)); list L=versal(j); // using default names def Px=L[1]; setring Px; show(Px); // show is a procedure from inout.lib listvar(ideal); // ___ Equations of miniversal base space ___: Js; // ___ Equations of miniversal total space ___: Fs; kill L; // the miniversal deformation of V(j) is the projection from the // miniversal total space to the miniversal base space: // { (A,B,C,D,E,F,x,y,z) | xy+A+Bz=0, y2+z2+x3+C+Dx+Ex2+Fy=0 } // --> { (A,B,C,D,E,F) } //---------------------------------------------------- // general case (cone over rational normal curve of degree 4): ring r1=0,(x,y,z,u,v),ds; matrix m[2][4]=x,y,z,u,y,z,u,v; ideal i=minor(m,2); // 2x2 minors of matrix m // Def_r will be the name of the miniversal base space with // parameters A(1),...,A(4) versal(i,0,"Def_r","A("); // the miniversal deformation of V(i) is the projection from the // miniversal total space to the miniversal base space: // { (A(1..4),x,y,z,u,v) | // -y^2+x*z+A(2)*x-A(3)*y=0, -y*z+x*u-A(1)*x-A(3)*z=0, // -y*u+x*v-A(3)*u-A(4)*z=0, -z^2+y*u-A(1)*y-A(2)*z=0, // -z*u+y*v-A(2)*u-A(4)*u=0, -u^2+z*v+A(1)*u-A(4)*v=0 } // --> { A(1..4) | // -A(1)*A(4) = A(3)*A(4) = -A(2)*A(4)-A(4)^2 = 0 } //---------------------------------------------------- LIB "tst.lib";tst_status(1);$