Robustness in Geometric Computations*

Geometric computation software tends to be fragile and fails occasionally. This robustness problem is rooted in the difficulty of making unambiguous decisions about incidence and nonincidence, fundamentally impairing layering the geometry software reliably. Additionally, geometric operations tend to have a large number of special and singular cases, further adding to the difficulty of creating dependable geometric software. We review the problem origins and ways to address it.