  It is well known that the containment problem (as well as the equivalence
problem) for semilinear sets is $\log$-complete in $\Pi_2^p$. It had been shown
quite recently that already the containment problem for multi-dimensional
linear sets is $\log$-complete in $\Pi_2^p$ (where hardness even holds for a
unary encoding of the numerical input parameters). In this paper, we show that
already the containment problem for $1$-dimensional linear sets (with binary
encoding of the numerical input parameters) is $\log$-hard (and therefore also
$\log$-complete) in $\Pi_2^p$. However, combining both restrictions (dimension
$1$ and unary encoding), the problem becomes solvable in polynomial time.
