Depth reduction of a class of Witten zeta functions
  We show that if a,b,c,d,f are positive integers such that a+b+c+d+f is even, then the Witten zeta value zeta_{sl(4)}(a,b,c,d,0,f) is expressible in terms of Witten zeta functions with fewer arguments. 
David M. Bradley, Tianxin Cai and Xia Zhou
math.NT