This package provides tools for calculating tangent and obstruction spaces as well as power series solutions for deformation problems involving isolated singularities and projective schemes.
A basic description of the package's approach to deformation problems can be found at the documentation node for versalDeformation. For details and mathematical background seeThe numerous examples presented in the documentation nodes for versalDeformation and localHilbertScheme are classical deformation problems, considered in the following articles:
The author thanks Jan Christophersen for helpful hints, especially regarding the computation of T2.
Version 1.0 of this package was accepted for publication in volume 4 of the journal The Journal of Software for Algebra and Geometry: Macaulay2 on 2012-06-05, in the article Versal deformations and local Hilbert schemes. That version can be obtained from the journal or from the Macaulay2 source code repository, after installing subversion, with the following shell command:
svn export -r 14710 svn://svn.macaulay2.com/Macaulay2/trunk/M2/Macaulay2/packages/VersalDeformations.m2
The following command will display the log messages accompanying any changes to the file in the repository since publication.
svn log -r 14711:HEAD svn://svn.macaulay2.com/Macaulay2/trunk/M2/Macaulay2/packages/VersalDeformations.m2
The following command will summarize the changes to the file in the repository since publication, in the format the program diff uses: lines starting with + have been added, and lines starting with - have been removed. (Changes to white space or end of line style will not be reported.)
svn diff -x "-b --ignore-eol-style" -r 14710:HEAD svn://svn.macaulay2.com/Macaulay2/trunk/M2/Macaulay2/packages/VersalDeformations.m2
The differences between two releases in the repository mentioned in the log can be displayed by replacing 14710:HEAD by the pair of release numbers separated by a colon.