Relative Gap in ANTIGONE output

Archiver · April 7, 2014, 10:20am

Hello everyone,

I have a question about the output when solving with ANTIGONE. It is a MINLP.

Part of the output is like this:

Time (s) Nodes explored Nodes remaining Best possible Best found Relative Gap

Searching for feasible solutions with 18 starting points at tree level 0 -
31 1 1 +4.200e+011 -6.466e+005 –
45 1 1 +3.360e+011 -6.466e+005 –
55 1 1 +3.120e+011 -2.831e+005 –

209 1 1 +3.120e+011 +4.882e+005 –
218 1 1 +3.120e+011 +4.882e+005 –
227 1 1 +3.120e+011 +4.882e+005 –
241 1 1 +3.120e+011 +4.882e+005 –

Current Best Poss: Current Best Found:

So what does a relative gap of “–” mean? Is it due to the relative gap too large? Is this normal when solving MINLP?
What about the meaning of “Current Best Poss”?

Many thanks!

Linlin

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Archiver · April 7, 2014, 3:49pm

Dear Linlin,

Many thanks for your question.

An optimality gap of “–” means that the gap is currently larger than 100%.

When you terminate the model, “Best Poss” is the best possible bound the global solution; it looks like you have a maximisation problem, so the very best that ANTIGONE has deduced (deterministically) is that the global optimum has to be at +3.120e+011 or less. “Best Current” is the best feasible solution found thus far (+4.882e+005); this is the best heuristic thus far.

Kind regards,

Ruth

On Monday, April 7, 2014 9:20:03 AM UTC+1, Linlin wrote: