User:A2569875/Coxeter–Dynkin diagram for wikidata

• see here Wikipedia_talk:WikiProject_Mathematics#about_Coxeter–Dynkin_diagram, and here Wikidata:Project_chat#datatype_for_en:Coxeter–Dynkin_diagram?.
• Examples:

2 21 polytope (Q4633288) → → x3o3o3o3o *c3o

cube (Q812880) → → x-4-o-3-o

Hessian polyhedron (Q27998992) → → x₃-3-o₃-3-o₃

pentagram (Q182186) → → x-5/2-o