A universal deformation ring which is not a complete intersection ring

Bleher and Chinburg recently used modular representation theory to produce an example of a linear representation of a finite group whose universal deformation ring is not a complete intersection ring. We prove this by using only elementary cohomological obstruction calculus. To cite this article: J. Byszewski, C. R. Acad. Sci. Paris, Ser. I 343 (2006).