Improved decision in presence of assumption

[rajdeep87]

With assumptions in the program, the decision heuristic can exploit the assumption statement to generate decisions on relevant variables such that the assumption constraint holds true.
For example, assume(x+y>4), the decisions can be x>=2 and y>=3.

This is irrespective of the fact that the octagonal constraints in the trail may not be able to derive the lower and upper bound of variable x and y, in which case a normal (less aggressive) decision heuristic would not be able to perform accurate splitting and hence can not take advantage of the assumption as shown above.