2 research outputs found
On the Termination of Linear and Affine Programs over the Integers
The termination problem for affine programs over the integers was left open
in\cite{Braverman}. For more that a decade, it has been considered and cited as
a challenging open problem. To the best of our knowledge, we present here the
most complete response to this issue: we show that termination for affine
programs over Z is decidable under an assumption holding for almost all affine
programs, except for an extremely small class of zero Lesbegue measure. We use
the notion of asymptotically non-terminating initial variable values} (ANT, for
short) for linear loop programs over Z. Those values are directly associated to
initial variable values for which the corresponding program does not terminate.
We reduce the termination problem of linear affine programs over the integers
to the emptiness check of a specific ANT set of initial variable values. For
this class of linear or affine programs, we prove that the corresponding ANT
set is a semi-linear space and we provide a powerful computational methods
allowing the automatic generation of these sets. Moreover, we are able to
address the conditional termination problem too. In other words, by taking ANT
set complements, we obtain a precise under-approximation of the set of inputs
for which the program does terminate.Comment: arXiv admin note: substantial text overlap with arXiv:1407.455