Published online by Cambridge University Press: 13 March 2020
In this paper, we study the growth of fine Selmer groups in two cases. First, we study the growth of fine Selmer ranks in multiple  $\mathbb{Z}_{p}$-extensions. We show that the growth of the fine Selmer group is unbounded in such towers. We recover a sufficient condition to prove the
$\mathbb{Z}_{p}$-extensions. We show that the growth of the fine Selmer group is unbounded in such towers. We recover a sufficient condition to prove the  $\unicode[STIX]{x1D707}=0$ conjecture for cyclotomic
$\unicode[STIX]{x1D707}=0$ conjecture for cyclotomic  $\mathbb{Z}_{p}$-extensions. We show that in certain non-cyclotomic
$\mathbb{Z}_{p}$-extensions. We show that in certain non-cyclotomic  $\mathbb{Z}_{p}$-towers, the
$\mathbb{Z}_{p}$-towers, the  $\unicode[STIX]{x1D707}$-invariant of the fine Selmer group can be arbitrarily large. Second, we show that in an unramified
$\unicode[STIX]{x1D707}$-invariant of the fine Selmer group can be arbitrarily large. Second, we show that in an unramified  $p$-class field tower, the growth of the fine Selmer group is unbounded. This tower is non-Abelian and non-
$p$-class field tower, the growth of the fine Selmer group is unbounded. This tower is non-Abelian and non- $p$-adic analytic.
$p$-adic analytic.