“…As mentioned in the Introduction, under the assumption that Greenberg's conjecture holds, it seems that the Galois group G = Gal(L(k ∞ )/k ∞ ) for totally real k ∞ has similar properties to the Galois group of a 2-class field tower of a finite extension of Q. By the results of Kisilevsky [10] and Benjamin-Snyder [5], all the types Q 2 m , D 2 m , SD 2 m , (2, 2) appear as the Galois groups of 2-class field towers of quadratic fields. From this point of view, we have the following question.…”