We consider braids on $m+n$ strands, such that the first $m$ strands are trivially fixed. We denote the set of all such braids by $B_{ m,n}$. Via concatenation $B_{ m,n}$ acquires a group structure. The objective of this paper is to find a presentation for $B_{ m,n}$ using the structure of its corresponding pure braid subgroup, $P_{ m,n}$, and the fact that it is a subgroup of the classical Artin group $B_{ m+n}$. Then we give an irredundant presentation for $B_{ m,n}$. The paper concludes by showing that these braid groups or appropriate cosets of them are related to knots in handlebodies, in knot complements and in c.c.o. 3--manifolds.
Categories: math.GT math.QA