“…Specifically, we consider the following optimization problem that aims to minimize the predictability notion introduced by Box and Tiao (
1977) while ensuring sparsity and volatility:
where
are symmetric and positive definite, ϕ is a positive number,
denotes the number of nonzero entries of a vector, and
with
. Recently, several statistical proxies have been introduced to capture mean‐reversion property (Cuturi and d'Aspremont,
2016; d'Aspremont et al.,
2005). For example, the following semidefinite program (SDP) relaxation‐based model is proposed (Cuturi and d'Aspremont,
2016) :
…”