[gecode-users] model with float variables sometimes hangs during search

[Christian Schulte]

Hi,

 

This could be a feature and not a bug in that constraint propagation is just
very slow to converge. For floating point numbers there is this risk.

 

I would not know what to suggest without knowing how the model looks like
but I am also not an expert in floating point. Vincent: do you have an idea?

 

Cheers

Christian

 

--

Christian Schulte, www.gecode.org/~schulte

Professor of Computer Science, KTH, cschulte at kth.se

Expert Researcher, SICS, cschulte at sics.se

 

From: users-bounces at gecode.org [mailto:users-bounces at gecode.org] On Behalf
Of Kurt Van Den Branden
Sent: Wednesday, April 15, 2015 4:00 PM
To: users at gecode.org
Subject: [gecode-users] model with float variables sometimes hangs during
search

 

hi, 

I have a Gecode model that uses float variables. 
I use a BAB searchengine with a Search::TimeStop object to interrupt the 
search when it takes too long. 

I noticed that when the model is created with certain parameters, the 
search isn't interrupted at the requested timelimit. 
it either continues a lot longer than allowed, or it doesn't stop at all. 

in these cases, the debugger shows that it's the method Space::status that
doesn't return sometimes. 
it keeps on propagating and never stops. 

I haven't been able to reproduce this with a limited test model yet. 

Does anybody have tips on what could cause this problem? 

Kind Regards,

Kurt Van Den Branden | Agfa Graphics

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