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D.6.5.2 mod_versal
Procedure from library deform.lib (see deform_lib).
- Usage:
- mod_versal(Mo,Io[,d,any]); Io=ideal, Mo=module, d=int, any =list
- Compute:
- miniversal deformation of coker(Mo) over Qo=Po/Io, Po=basering;
- Return:
- list L of 4 rings:
L[1] extending the basering Po by new variables given by
"A,B,.." (deformation parameters); the new variables precede
the old ones, the ordering is the product of "ls" and "ord(Po)"
L[2] = L[1]/Io extending Qo,
L[3] = the embedding ring of the versal base space,
L[4] = L[1]/(Io+Js) ring of the versal deformation of coker(Ms).
In the ring L[1] the following matrices are stored:
Js = giving the versal base space (obstructions),
Fs = giving the versal family of Mo,
Rs = giving the lifting of syzygies Lo=syz(Mo).
If d is defined (!=0), it computes up to degree d.
If 'any' is defined and any[1] is no string, interactive version.
Otherwise 'any' is interpreted as a list of predefined strings:
"my","param","order","out":
("my" internal prefix, "param" is a letter (e.g. "A") for the
name of the first parameter or (e.g. "A(") for index parameter
variables, "order" ordering string for ring extension), "out" name
of output file).
- Note:
- printlevel < 0 no additional output,
printlevel >=0,1,2,.. informs you, what is going on,
this proc uses 'execute'.
Example:
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