1989/01/01 by Kenneth E. Appel, Wolfgang Haken · 8 citations
Computer Science · #Computational Geometry and Mesh Generation #Graph Labeling and Dimension Problems
paper · doi:10.1090/conm/098
openalex publication_date 1989/01/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/04
The following theorem is proved.THEOREM .Every planar map can be colored with at most four colors.