Artin group
group admitting a presentation whose relations are of the form stst…= tsts…, where both sides have equal lengths, such that there exists at most 1 relation for each pair of distinct generators s, t
braid group
mathematical concept in knot theory
free abelian group
commutative group whose elements are unique integer combinations of basis elements
free group
free object in the category of groups; a group admitting a presentation without any relations