Which weakly ramified group actions admit a universal formal deformation?

Byszewski, Jakub; Cornelissen, Gunther

Annales de l'Institut Fourier, Volume 59 (2009) p. 877-902

A universal deformation ring which is not a complete intersection ring

Byszewski, Jakub

Comptes Rendus. Mathématique, Volume 343 (2006) p. 565-568