© 1995 by London Mathematical Society
© The London Mathematical Society
Lech's Conjecture on Deformations of Singularities and Second Harrison Cohomology
Max-Planck-Institut für Mathematik, Gottfried-Claren-Straße 26 W-5300 Bonn 3, Germany
Universität zu Köln, Mathematisches Institut Weyertal 86-90, W-5000 Köln 41, Germany
Received 6 January 1993. Revision received 2 April 1993.
Let B0 be a local singularity of dimension d. Then we consider the problem of Lech, whether for every deformation (A, m)
(B, n) of B0 the inequality
between the Hilbert functions is true, and give a positive answer in the case that the formal versal deformation of B0 is a base change of an algebraic family (R, M)
(S, N), where R is regular and dim S = dim R + d.
So one would hope to lift versal deformations in that way. There are obstructions against this in certain second Harrison cohomology groups.