We compute the zeta functions enumerating graded ideals in the graded Lie rings associated with the free d-generator Lie rings f c,d of nilpotency class c for all c ď 2 and for pc, dq P tp3, 3q, p3, 2q, p4, 2qu. We apply our computations to obtain information about p-adic, reduced, and topological zeta functions, in particular pertaining to their degrees and some special values.Date: June 15, 2016. 2000 Mathematics Subject Classification. 17B70, 11M41, 11S40. Key words and phrases. Graded ideal zeta functions, free nilpotent Lie rings, local functional equations.Ÿgr f 2,d pOq psq for all d ě 2 in Section 4 and those for pc, dq P tp3, 2q, p4, 2qu in Section 5 of the current paper.The paper's most involved result is the computation, in Section 3, of the graded ideal zeta function of f 3,3 pOq. To this end we compute an explicit formula for ζ Ÿgr f 3,3 poq psq, valid for all finite extension o of the p-adic integers Z p , where p is a prime, viz. a local ring of the form o " O p for a nonzero prime ideal p of O lying above p. Theorem 1.1. There exists an explicitly determined rational function W Ÿgr 3,3 P QpX, Y q such that, for all primes p and all finite extensions o of Z p , with residue cardinality q, ζ Ÿgr f 3,3 poq psq " W Ÿgr 3,3 pq, q´sq.
It may be written as Wa polynomial of degree 115 in X and 131 in Y , and N 3,3 P QrX, Y s is a polynomial of degree 81 in X and 108 in Y .The rational function W Ÿgr 3,3 satisfies the functional equationWe note that the Witt function W 3 (cf. (1.2)) takes the values pW 3 p1q, W 3 p2q, W 3 p3qq " p3, 3, 8q and that 115´81 " 34 "`3 2˘``3 2˘``8 2˘a nd 131´108 " 23 " 3¨3`2¨3`1¨8; cf. Conjecture 6.2.Our proof of Theorem 1.1 yields W Ÿgr 3,3 as a sum of 15 explicitly given summands, listed essentially in Section 3.2. We do not reproduce the "final" outcome of this summation here, as the numerator N 3,3 of W Ÿgr 3,3 fills several pages. We do record, however, several corollaries of the explicit formula for W Ÿgr 3,3 . The first corollary concerns analytic properties of the global zeta function ζ Ÿgr f 3,3 pOq psq.Corollary 1.2. The global graded ideal zeta function ζ Ÿgr f 3,3 pOq psq converges on ts P C | Repsq ą 3u and may be continued meromorphically to ts P C | Repsq ą 14{9u.