Resolution
Global GMS
ES Strata
Build. Blocks
Comb. Appl.
HCA Proving
Arrangements
Branches
Classify
Coding
Deformations
Equidim Part
Existence
Finite Groups
Flatness
Genus
Hilbert Series
Membership
Nonnormal Locus
Normalization
Primdec
Puiseux
Plane Curves
Saturation
Solving
Space Curves
Spectrum
M. Saito's A0 and A1
Task: Compute M. Saito's endomorphisms
which satisfy:
A1 is semisimple with eigenvalues being the spectral numbers of f added by 1, and

ring R=0,(x,y),ds;
poly f=x5+x2y2+y5;
LIB "gaussman.lib";


The command tmatrix(f) returns a list L :

  • L[1] contains A0 with respect to the basis matrix(L[4])*L[3] of H''/H'.
  • L[2] contains A1 with respect to the basis matrix(L[4])*L[3] of H''/H'.
  • L[4] contains a monomial vector space basis for H''/H'.
list L=tmatrix(f);
print(L[1]); // the matrix A_0
==>
0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,
1,0,0,0,0,0,0,0,0,0,0
print(L[2]); // the matrix A_1
==>
1/2,0,   0,   0,   0,   0,  0,    0,    0,    0,    0,
0,  7/10,0,   0,   0,   0,  0,    0,    0,    0,    0,
0,  0,   7/10,0,   0,   0,  0,    0,    0,    0,    0,
0,  0,   0,   9/10,0,   0,  0,    0,    0,    0,    0,
0,  0,   0,   0,   9/10,0,  0,    0,    0,    0,    0,
0,  0,   0,   0,   0,   1,  0,    0,    0,    0,    0,
0,  0,   0,   0,   0,   0,  11/10,0,    0,    0,    0,
0,  0,   0,   0,   0,   0,  0,    11/10,0,    0,    0,
0,  0,   0,   0,   0,   0,  0,    0,    13/10,0,    0,
0,  0,   0,   0,   0,   0,  0,    0,    0,    13/10,0,
0,  0,   0,   0,   0,   0,  0,    0,    0,    0,    3/2
print(matrix(L[4])*L[3]); // the chosen basis of H''/H'
==>
-1+2xy-1445/64y5, 16x+125y4, 16y+125x4, 4x2+5y3, 4y2+5x3, xy+85/8y5, y3, x3, y4, x4, 1/2y5

KL, 06/03 http://www.singular.uni-kl.de