Before revision: Updating an abstract Voronoi diagram in linear time, after deletion of one site , has been an open problemfor a long time. Similarly for various concrete Voronoi diagrams of generalized sites, other than points .
After revision: Updating an abstract Voronoi diagram in linear time, after deletion of one site in linear time has been a well-known open problem; similarly, for concrete Voronoi diagrams of generalized sites, other than points .