  In many QBF encodings, sequences of Boolean variables stand for binary
representations of integer variables. Examples are state labels in bounded
model checking or actions in planning problems. Often not the full possible
range is used, e.g., for representing six different states, three Boolean
variables are required, rendering two of the eight possible assignments
irrelevant for the solution of the problem. As QBF solvers do not have any
domain-specific knowledge on the formula they process, they are not able to
detect this pruning opportunity.
  In this paper, we introduce the idea of int-splits, which provide
domain-specific information on integer variables to QBF solvers. This is
particularly appealing for parallel Divide-and-Conquer solving which partitions
the search space into independently solvable sub-problems. Using this
technique, we reduce the number of generated sub-problems from a full expansion
to only the required subset. We then evaluate how many resources int-splits
save in problems already well suited for D&C. In that context, we provide a
reference implementation that splits QBF formulas into many sub-problems with
or without int-splits and merges results. We finally propose a comment-based
optional syntax extension to (Q)DIMACS that includes int-splits and is suited
for supplying proposed guiding paths natively to D&C solvers.
