Possible clash between density axiom and epsilon separation between timepoints #14
Description
The density axiom requires the solver to fill all concrete steps if the abstract step is used. In order to fulfill this requirement, the solver may possibly apply non-mutex events in consecutive steps, rather than grouping them in a single step. If we add the constraints t_{i-1} + epsilon <= t_i between the timepoints, we could introduce an error of n * epsilon where n is the number of concrete steps. This may result in a wrong answer if there exists a concrete solution with a difference in makespan lower than n * epsilon, and an even better concrete solution that cannot be encoded in n concrete steps, which would not be returned.