2-Good Rings

On quantitative aspects of the unit sum number problem

“…Zelinsky showed that every endomorphism of a vector space V over a division ring D can be written as the sum of two automorphisms, unless D is not the field with two elements and V is of dimension 1. Similar results were obtained for other endomorphism rings (for an overview see [13]). …”

The additive unit structure of complex biquadratic fields

“…Zelinsky proved, if V is a vector space over a division ring D, then every linear transformation can be written as the sum of two automorphisms unless dim V = 1 and D is the field of two elements. Zelinsky's work gave rise to many investigations of rings that are generated by their units (see [9] for an overview). These investigations led Goldsmith, Pabst and Scott [4] to the following definition: Definition 1.…”

Rings which are generated by their units: a graph theoretical approach

“…Interest in this topic increased recently after they defined the unit sum number in [4]. For additional historical background the reader is referred to the paper [10], which also contains references to recent work in this area. Also see [9] for a survey of rings which are generated by their units.…”