the solving algorithm has a linear complexity with respect to $n$.
First of all, Filler \emph{et al.} compute the matrix $H$
-by placing a small sub-matrix $\hat{H}$ of size $h × w$ next
+by placing a small sub-matrix $\hat{H}$ next
to each other and by shifting down by one row.
Thanks to this special form of $H$, one can represent
any solution of $m=Hy$ as a path through a trellis.
