Hypervolume representation and comparison

[nikohansen]

The line

pycomocma/comocma/como.py

Line 471 in 036abf6

kernel.tell(offspring, [-float(u) for u in hypervolume_improvements])

converts the HV computation result to float. This seems to defeat the very idea why Fractions are available in the moarchiving module.

Possible solutions:

• check the converted floats for equality and when equal values are found, subtract the minimal value still in Fraction type before the conversion. This could also be optional.
• make the cma package work with Fraction and remove the conversion.

[nikohansen]

I believe the current cma package can now deal with Fractions. Hence the idea would be to see whether we still need the float in the following assignment of the values that are later passed to tell (line 500 in development@gitlab):

kernel._last_offspring_neg_UHVI_values = [-float(self.indicator_front.hypervolume_improvement(point))