Since ArcGIS Desktop 9, I always found the four color theorem great to symbolized to depict layers with a lot of polygons (such as census tracts) so that no two adjacent polygons have the same color. It used to be called "Map Coloring - Four Color a Map" and basically applied the 4-color map theorem to a polygon file by adding a column with integers. Howerver, it never really worked under ArcGIS Desktop 10 and was desperate to use it again, as explained here:
I now installed ArcGIS Pro 2.0 and perhaps ESRI included this symbolization style in their new GIS desktop application? For the time being, I cannot find anything such as "4-color map" tool... Is it somewhere included? Or is there any workaround or script with the new ArcGIS Pro 2.0?