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 Post subject: signature of the Milnor fibre
PostPosted: Sun Feb 22, 2009 7:01 pm 
I often need to compute the Milnor fibre signature for isolated hypersurface singularities. (Or maybe even the whole triple mu_+,mu_0,mu_-).

It seems that the only procedure in Singular is first to compute the spectrum (with gmssing.lib). Then in it one has to count (by hands?) the values in the needed regions.

Is there a separate command computing the signature? (The spectrum runs very slowly and for moderately complicated cases doesn't give any result in the reasonable time.)

Or maybe at least for plane curves or surfaces which are suspensions of curves..

thanks in advance,
Dmitry


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PostPosted: Tue Feb 24, 2009 4:43 pm 

Joined: Mon Aug 29, 2005 9:22 am
Posts: 41
Location: Kaiserslautern, Germany
At the moment there is no other way to compute the signature in Singular. You may use spectrumnd for nondegenerate examples (which should be faster).

(It should be easy to avoid hand computation by writing a few lines of code
in Singular.)


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PostPosted: Sun Mar 29, 2009 5:35 pm 

Joined: Mon Aug 29, 2005 9:22 am
Posts: 41
Location: Kaiserslautern, Germany
Addendum:

G. Pfister used your question to make the algorithmic theory of the signature of the Milnor fibre a thesis project for a student.
Of course we hope that the project will be successful and that, at the end, we will have a good implementation in Singular.
However, this will take some time.


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