Examples 5.5 . [02ES]
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Examples 5.5.
Let be a normal algebraic surface. The following are equivalent:
- (1)
has only canonical singularities.
- (2)
is locally analytically isomorphic to , a finite subgroup.
- (3)
The exceptional divisors of the minimal resolution of , have simple normal crossings, their components are (-2) smooth rational curves, their incidence graphs are of type A-D-E (Du Val singularities).
The log terminal surface singularities are precisely the singularities of the form , a finite subgroup.