The universal character ring of the \((-2,2m+1,2n)\)-pretzel link (Q2855483)

It is known that the quotient of the universal character ring of a finitely presented group \(G\) by its nil-radical is equal to the ring of regular functions of its character variety \(X(G)\). When the nil-radical is trivial the universal character ring is said to be reduced. So far there are only a few groups for which the universal character ring is known to be reduced: free groups, surface groups, two-bridge knot groups, torus knot groups, the \((-2,3,2n+1)-\)pretzel knot groups and two-bridge link groups.NEWLINENEWLINEIn this paper, the author calculates explicitely the universal character ring of the \((-2,2m+1,2n)-\)pretzel link and proves that it is reduced for all integers \(m\) and \(n\).