egységcsoport
An egységcsoport, translated to English as "unit group" or sometimes "identity group," is a fundamental concept in abstract algebra, particularly in the study of groups. It is the simplest possible group, consisting of only a single element. This single element is the identity element of the group. By definition, the identity element, when combined with itself using the group operation, results in the identity element itself. In addition, the inverse of the identity element is the identity element. Therefore, the egységcsoport satisfies all the axioms of a group: closure, associativity, the existence of an identity element, and the existence of an inverse element for each element. This group is always abelian, meaning the group operation is commutative. The egységcsoport is unique up to isomorphism. It plays a crucial role in understanding more complex group structures, often serving as a building block or a trivial case in proofs and constructions. In various algebraic contexts, such as ring theory or field theory, the concept of a unit group refers to the set of invertible elements under multiplication, which forms a group itself. However, the term "egységcsoport" in its most basic sense refers to the group with just one element.