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A.4.5 Deformations

  • The libraries sing.lib, respextively deform.lib, contain procedures to compute total and base space of the miniversal (= semiuniversal) deformation of an isolated complete intersection singularity, respectively of an arbitrary isolated singularity.
  • The procedure deform in sing.lib returns a matrix whose columns represent all 1st order deformations. More precisely, if
  • The procedure versal in deform.lib computes a formal miniversal deformation up to a certain order which can be prescribed by the user. For a complete intersection the 1st order part is already miniversal.
  • The procedure versal extends the basering to a new ring with additional deformation parameters which contains the equations for the miniversal base space and the miniversal total space.
  • There are default names for the objects created, but the user may also choose their own names.
  • If the user sets printlevel=2; before running versal, some intermediate results are shown. This is useful since versal is already complicated and might run for some time on more complicated examples. (type help versal;)

We compute for the same examples as in the section T1 and T2 the miniversal deformations:

 


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