A multi-index is said to be increasing if its entries are ordered in increasing order, i.e. for \(I=(i_1,\ldots,i_k)\) we have
\begin{equation*} i_1<\ldotsA multi-index is said to be increasing if its entries are ordered in increasing order, i.e. for \(I=(i_1,\ldots,i_k)\) we have
\begin{equation*} i_1<\ldots