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industrial-optimization-group / desdeo-mcdm

Contains traditional optimization techniques from the field of Multiple-criteria decision-making. For example, methods belonging to the NIMBUS and NAUTILUS families can be found here.
MIT License
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Bug in NAUTILUS I implementation #47

Closed light-weaver closed 7 months ago

light-weaver commented 8 months ago

Technically, you don't need two extra elements in these arrays. Only one will do the trick if the bug is fixed.

https://github.com/industrial-optimization-group/desdeo-mcdm/blob/442021c906d62ceb2258d045b23e1d7df9058fe8/desdeo_mcdm/interactive/Nautilus.py#L472-L477

Initially, the zeroth element should be set, not the first element as done here (first step number is 1): https://github.com/industrial-optimization-group/desdeo-mcdm/blob/442021c906d62ceb2258d045b23e1d7df9058fe8/desdeo_mcdm/interactive/Nautilus.py#L493-L494

In all subsequent steps, you should not add 1 to the step number: https://github.com/industrial-optimization-group/desdeo-mcdm/blob/442021c906d62ceb2258d045b23e1d7df9058fe8/desdeo_mcdm/interactive/Nautilus.py#L527-L528

There are multiple instances of that error, that should be fixed.

Finally, changing the number of iterations does not work as intended:

https://github.com/industrial-optimization-group/desdeo-mcdm/blob/442021c906d62ceb2258d045b23e1d7df9058fe8/desdeo_mcdm/interactive/Nautilus.py#L564

The above line implies that the user provided number is the total number (including iterations that have already taken place).

https://github.com/industrial-optimization-group/desdeo-mcdm/blob/442021c906d62ceb2258d045b23e1d7df9058fe8/desdeo_mcdm/interactive/Nautilus.py#L576

The line above implies that the user provided number is the new remaining steps.

The two lines are in conflict, leading to the algorithm never working if one takes a step back.

light-weaver commented 8 months ago

Accept the pull request if you agree with the changes. Check if similar changes need to be made to other NAUTILUS implementations.

I also did not reduce the number of elements in the arrays in case they were being used for some other reason. Though in my test, the last element is always left to be None.