  We revisit the problem of \textit{online linear optimization} in case the set
of feasible actions is accessible through an approximated linear optimization
oracle with a factor $\alpha$ multiplicative approximation guarantee. This
setting is in particular interesting since it captures natural online
extensions of well-studied \textit{offline} linear optimization problems which
are NP-hard, yet admit efficient approximation algorithms. The goal here is to
minimize the $\alpha$\textit{-regret} which is the natural extension of the
standard \textit{regret} in \textit{online learning} to this setting.
  We present new algorithms with significantly improved oracle complexity for
both the full information and bandit variants of the problem. Mainly, for both
variants, we present $\alpha$-regret bounds of $O(T^{-1/3})$, were $T$ is the
number of prediction rounds, using only $O(\log{T})$ calls to the approximation
oracle per iteration, on average. These are the first results to obtain both
average oracle complexity of $O(\log{T})$ (or even poly-logarithmic in $T$) and
$\alpha$-regret bound $O(T^{-c})$ for a constant $c>0$, for both variants.
