Let R be a ring. The unit graph of R, denoted by G (R), is the simple graph defined on all elements of R, and where two distinct vertices x and y are linked by an edge if and only if x+y is a unit of ...

Let G be a finite group, and let cd (G) be the set of irreducible character degrees of G. The degree graph Δ (G) is the graph whose set of vertices is the set of primes that divide degrees in cd (G), ...