Top
Back: D.5.1.1 basicinvariants
Forward: D.5.1.3 corank
FastBack: D. SINGULAR libraries
FastForward: E. Release Notes
Up: D.5.1 classify_lib
Top: Singular 2-0-4 Manual
Contents: Table of Contents
Index: F. Index
About: About This Document

D.5.1.2 classify

Procedure from library classify.lib (see classify_lib).

Usage:

classify(f); f=poly

Compute:

normal form and singularity type of f with respect to right equivalence, as given in the book "Singularities of differentiable maps, Volume I" by V.I. Arnold, S.M. Gusein-Zade, A.N. Varchenko

Return:

normal form of f, of type poly

Remark:

This version of classify is only beta. Please send bugs and comments to: "Kai Krueger" <krueger@mathematik.uni-kl.de>
Be sure to have at least Singular version 1.0.1. Updates can be found at:
URL=http://www.mathematik.uni-kl.de/~krueger/Singular/

Note:

type init_debug(n); (0 <= n <= 10) in order to get intermediate information, higher values of n give more information.
The proc creates several global objects with names all starting with @, hence there should be no name conflicts

Example:

 
LIB "classify.lib";
ring r=0,(x,y,z),ds;
poly f=(x2+3y-2z)^2+xyz-(x-y3+x2*z3)^3;
classify(f);
→ About the singularity :
→           Milnor number(f)   = 4
→           Corank(f)          = 2
→           Determinacy       <= 5
→ Guessing type via Milnorcode:   D[k]=D[4]
→ 
→ Computing normal form ...
→ I have to apply the splitting lemma. This will take some time....:-)
→    Arnold step number 4
→ The singularity
→    -x3+3/2xy2+1/2x3y-1/16x2y2+3x2y3
→ is R-equivalent to D[4].
→    Milnor number = 4
→    modality      = 0
→ 2z2+x2y+y3
init_debug(3);
→ Debugging level change from  0  to  3
classify(f);
→ Computing Basicinvariants of f ...
→ About the singularity :
→           Milnor number(f)   = 4
→           Corank(f)          = 2
→           Determinacy       <= 5
→ Hcode: 1,2,1,0,0
→ Milnor code :  1,1,1
→ Debug:(2):  entering HKclass3_teil_1 1,1,1
→ Debug:(2):  finishing HKclass3_teil_1
→ Guessing type via Milnorcode:   D[k]=D[4]
→ 
→ Computing normal form ...
→ I have to apply the splitting lemma. This will take some time....:-)
→ Debug:(3):  Split the polynomial below using determinacy:  5
→ Debug:(3):  9y2-12yz+4z2-x3+6x2y-4x2z+xyz+x4+3x2y3
→ Debug:(2):  Permutations: 3,2,1
→ Debug:(2):  Permutations: 3,2,1
→ Debug:(2):  rank determined with Morse rg= 1
→ Residual singularity f= -x3+3/2xy2+1/2x3y-1/16x2y2+3x2y3
→ Step 3
→    Arnold step number 4
→ The singularity
→    -x3+3/2xy2+1/2x3y-1/16x2y2+3x2y3
→ is R-equivalent to D[4].
→    Milnor number = 4
→    modality      = 0
→ Debug:(2):  Decode:
→ Debug:(2):  S_in= D[4]   s_in= D[4]                          
→ Debug:(2):  Looking for Normalform of  D[k] with (k,r,s) = ( 4 , 0 , 0 )
→ Debug:(2):  Opening Singalarity-database:  
→  DBM: NFlist
→ Debug:(2):  DBMread( D[k] )= x2y+y^(k-1) .
→ Debug:(2):  S= f = x2y+y^(k-1);  Tp= x2y+y^(k-1) Key= I_D[k]
→ Polynom f= x2y+y3   crk= 2   Mu= 4  MlnCd= 1,1,1
→ Debug:(2):  Info= x2y+y3
→ Debug:(2):  Normal form NF(f)= 2*x(3)^2+x(1)^2*x(2)+x(2)^3
→ 2z2+x2y+y3

Top Back: D.5.1.1 basicinvariants Forward: D.5.1.3 corank FastBack: D. SINGULAR libraries FastForward: E. Release Notes Up: D.5.1 classify_lib Top: Singular 2-0-4 Manual Contents: Table of Contents Index: F. Index About: About This Document
            User manual for Singular version 2-0-4, October 2002, generated by texi2html.