  Augmented B-trees (aB-trees) are a broad class of data structures. The
seminal work "succincter" by Patrascu showed that any aB-tree can be stored
using only two bits of redundancy, while supporting queries to the tree in time
proportional to its depth. It has been a versatile building block for
constructing succinct data structures, including rank/select data structures,
dictionaries, locally decodable arithmetic coding, storing balanced
parenthesis, etc.
  In this paper, we show how to "dynamize" an aB-tree. Our main result is the
design of dynamic aB-trees (daB-trees) with branching factor two using only
three bits of redundancy (with the help of lookup tables that are of negligible
size in applications), while supporting updates and queries in time polynomial
in its depth. As an application, we present a dynamic rank/select data
structure for $n$-bit arrays, also known as a dynamic fully indexable
dictionary (FID). It supports updates and queries in $O(\log n/\log\log n)$
time, and when the array has $m$ ones, the data structure occupies \[
  \log\binom{n}{m} + O(n/2^{\log^{0.199}n}) \] bits. Note that the update and
query times are optimal even without space constraints due to a lower bound by
Fredman and Saks. Prior to our work, no dynamic FID with near-optimal update
and query times and redundancy $o(n/\log n)$ was known. We further show that a
dynamic sequence supporting insertions, deletions and rank/select queries can
be maintained in (optimal) $O(\log n/\log\log n)$ time and with $O(n \cdot
\text{poly}\log\log n/\log^2 n)$ bits of redundancy.
