The lower independence number of a graph is the minimum size of a maximal independent vertex set in . The lower indepedence number is equivalent to the independent domination number (i.e., the minimum size of an independent dominating set; cf. Crevals and Östergård 2015, Ilić and Milošević 2017).
The (upper) independence number may be similarly defined as the largest size of an independent vertex set in (Burger et al. 1997).
The lower irredundance number , lower domination number , lower independence number , upper independence number , upper domination number , and upper irredundance number satsify the chain of inequalities
(Burger et al. 1997).