Assertion: abelian group's element | /r/HasProperty | a unit of r
Facets:
Source sentences:
text: So, an element u [member of] [R.sup.x] is a unit of R if there exist u' [member of] [R.sup.x] such that uu' = u'u = 1, and [R.sup.x] forms an abelian group under usual multiplication of R.