Mathematical Research Letters

Volume 8, Issue 6, November 2001 pp. 813-817.

The map $V\longrightarrow V/\!/G$ need not be separable

Authors: Ben Martin and Amnon Neeman
Author institution: The Hebrew University, and The Australian National University

Summary: We construct a vector space $V$ with a linear action of a reductive group $G$ such that the quotient map $V \longrightarrow V/\!/G$ (in the sense of geometric invariant theory) fails to be separable. This gives a counterexample to an assertion of Bardsley and Richardson.

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