Deep transfers of p-class tower groups

Abstract

Let p be a prime. For any finite p-group G, the deep transfers T(H,G'):H/H' --> G'/G'' from the maximal subgroups H of index (G:H)=p in G to the derived subgroup G' are introduced as an innovative tool for identifying G uniquely by means of the family of kernels kappa_d(G)=(ker(T(H,G')))_{(G:H)=p}. For all finite 3-groups G of coclass cc(G)=1, the family kappa_d(G) is determined explicitly. The results are applied to the Galois groups G=Gal(F_3^\infty/F) of the Hilbert 3-class towers of all real quadratic fields F=Q(d^1/2) with fundamental discriminants d>1, 3-class group Cl_3(F)~C_3*C_3, and total 3-principalization in each of their four unramified cyclic cubic extensions E/F. A systematic statistical evaluation is given for the complete range 1<d<5*10^6, and a few exceptional cases are pointed out for 1<d<64*10^6.