3. Conventions:

For the sake of simplicity, we have presented operators such as void add_dimension or void remove_dimension with only one parameter. However, as discussed in our documentation [QUE], the several parameters support is suggested since it improves the performance of these operators at algorithmic level, e.g. convex hull.

We propose in HQ interface some additional operators that can be considered redundant such as re-map and sort for the HQBasis class. We also introduce the getSize() operator, which is an abstract size of a HQSet. This size of a HQSet should provide heuristically defined information about how long the principal operators might need to finish their task. We suggest as well to unify the debugging functions, such as those in $C^3$, where we have boolean sc_consistent_p(Psysteme) or boolean sc_weak_consistent_p(Psysteme) .

The HQ interface is proposed after having studied the other four interfaces; as a result, for adaptations, wrapping functions are suggested. However, as we have seen in 4_subsec:issue_variable_assignment, wrapping functions for Octagon are not yet possible since dimension permutation operators are not available. The example with timeout management for POLYLIB (4_subsec:issue_control_execution_time) is another example that shows how hard this work can be.

In the next section, we discuss some important operators in detail. For the complete documentation of HQ, readers are referred to [QUE].