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Erik Hellsten
@erohe_gitlab
ok, cool! =)
Simon Spoorendonk
@spoorendonk
what are the constraints you add in the ttfcmcf?
the user cuts
^ @erohe_gitlab
Erik Hellsten
@erohe_gitlab
The first set of user cuts are the so called strong constraints of the form kKxijkyij\sum_{k\in K}x_{ij}^k \le y_{ij}, separated by inspection. The next are the lifted cover inequalities (though maybe the framwork already does that?)
Simon Spoorendonk
@spoorendonk
I will try and add the strong constraints in my test. Then I will look at what cuts I can get the framework to separate
found another branching bug to fix first though ...
Erik Hellsten
@erohe_gitlab
hehe, I know the feeling. Finding bugs seems to be a dominant part of my life at the moment..
but ok, yeah, whenever I could be of any help, you just say so =)
Simon Spoorendonk
@spoorendonk
and it just continues. Maybe that is why people become managers at some point!
Erik Hellsten
@erohe_gitlab
Yeah, I suppose ^^
Or professors
Simon Spoorendonk
@spoorendonk
same same
Erik Hellsten
@erohe_gitlab
yeah, I suppose so
Simon Spoorendonk
@spoorendonk

but ok, yeah, whenever I could be of any help, you just say so =)

I don't know how much time you have on your hands? And what kind of help you would find interesting?
Setting up models to expose stuff that does/doesn't work helps me a lot - like the ttfcmcf. In that direction I am locking into https://github.com/GregorCH/ipet to thoroughly test and track running times.

It could also go deeper into the c++ if you feel really confident!

It could also go deeper into the c++ if you feel really confident!

in digging in my well documented codebase...

Erik Hellsten
@erohe_gitlab
It would of course be interesting, and maybe (hopefully) one day I'll have time for that, but for now I already have 3 projects in queue somehow, and I have a tendency to dig myself deep in, once I begin with something. So for now I'll wait a bit with having a look at the c++ code =) But I would be happy to write a cover inequality separator in the python interface once you have the user cut-interface running, for example.
Simon Spoorendonk
@spoorendonk
:+1:
Simon Spoorendonk
@spoorendonk
I am thinking this would make ok sense
def callback(cb: CallbackModel, where: Where):
    if where == Where.PathMipCuts:
        relax = cb.relaxation

        for y in y_vars:
            e = (arcs[y.id].start, arcs[y.id].end)            
            xEdges = [x for k in range(k) for x in x_vars[k] if x.edge = e]
            xksum = sum([relax[x.id] for x in xEdges])

            if xksum > relax[y.id]:
                cb.addCut(xsum([ 1*x for x in xEdges]) <= y)
Erik Hellsten
@erohe_gitlab
Yeah, it seems great =) you want a capital K in "range(k)" on line 7. Maybe you want an error margin, and only add the cut if xksum > y + ϵ\epsilon? These programs tend to have some minor precision issues (just so you don't add a cut which is already in the model).
Simon Spoorendonk
@spoorendonk
:+1: I will see if I can get it ready for the presentation tomorrow. It's gonna be close
Erik Hellsten
@erohe_gitlab
I'm looking forward to see it =)
Simon Spoorendonk
@spoorendonk
me too :)
Simon Spoorendonk
@spoorendonk

tt_r10.1_12.csv

objval: 200126.99999999336

real 0m15.888s
user 4m6.219s
sys 0m4.533s

@erohe_gitlab ^
Simon Spoorendonk
@spoorendonk

Ok. The big one is hard

Process Node 514 (algo = PRICE_AND_CUT, phaseLast = PHASE_CUT) gLB = 56379.5 gUB = 59044 gap = 0.04726 time = 861.580

5 % after 15 min

tt_r18.1_12.csv

objval: 372254.0000000172

real 1m14.640s
user 15m30.381s
sys 0m10.323s

60 seconds without std::out
Simon Spoorendonk
@spoorendonk
On strong inequalities. Are we not talking xijkyijx_{ij}^k \leq y_{ij}
Simon Spoorendonk
@spoorendonk
and xijkdkyijx_{ij}^k \leq d^k y_{ij} for the other model
Simon Spoorendonk
@spoorendonk

with and without cuts in 06 example

Alps0208I Search completed.
Alps0261I Best solution found had quality 250351 and was found at depth 32
Alps0265I Number of nodes fully processed: 20
Alps0266I Number of nodes partially processed: 15
Alps0267I Number of nodes branched: 17
Alps0268I Number of nodes pruned before processing: 0
Alps0270I Number of nodes left: 0
Alps0272I Tree depth: 7
Alps0274I Search CPU time: 143.07 seconds
Alps0278I Search wall-clock time: 83.62 seconds

================ DECOMP Statistics [BEGIN]: ===============
Total Decomp = 83.60 100.00 35 3.51
Total Solve Relax = 0.00 0.00 0 0.00
Total Solve Relax App = 0.00 0.00 0 0.00
Total Solution Update = 0.79 0.94 109 0.05
Total Generate Cuts = 72.43 86.63 48 1.59
Total Generate Vars = 6.59 7.88 82 0.10
Total Compress Cols = 0.04 0.05 14 0.01
================ DECOMP Statistics [END ]: ===============

Node 32 process stopping on bound. This LB= 250366 Global UB= 250351.

Alps0208I Search completed.
Alps0261I Best solution found had quality 250351 and was found at depth 30
Alps0265I Number of nodes fully processed: 18
Alps0266I Number of nodes partially processed: 15
Alps0267I Number of nodes branched: 16
Alps0268I Number of nodes pruned before processing: 0
Alps0270I Number of nodes left: 0
Alps0272I Tree depth: 7
Alps0274I Search CPU time: 48.34 seconds
Alps0278I Search wall-clock time: 3.56 seconds

================ DECOMP Statistics [BEGIN]: ===============
Total Decomp = 3.54 100.00 33 0.31
Total Solve Relax = 0.00 0.00 0 0.00
Total Solve Relax App = 0.00 0.00 0 0.00
Total Solution Update = 0.86 24.17 134 0.05
Total Generate Cuts = 0.00 0.00 49 0.00
Total Generate Vars = 0.66 18.52 97 0.01
Total Compress Cols = 0.06 1.70 21 0.00
================ DECOMP Statistics [END ]: ===============

room for improvement
wonder why the pricing became so hard
Simon Spoorendonk
@spoorendonk

tt_r18.1_12.csv

objval: 372254.0000000172

real 1m14.640s
user 15m30.381s
sys 0m10.323s

Erik Hellsten
@erohe_gitlab
Hi!
I pushed some intital results for the smaller instances. Still need to run some of the bigger ones but I'll do it tonight.
Simon Spoorendonk
@spoorendonk
Cool. Awesome
Simon Spoorendonk
@spoorendonk
are your results single threaded? Just for comparison
and they are with the strong flow inequalities right?
Erik Hellsten
@erohe_gitlab
they are with dynamic strong inequalities, yes =)
ehm, yeah. more or less at least. I solve almost everything single core, except for when I solve the integer problem with the root node columns to generate an intial upper bound, which I by some reason solve with 4 cores. But that makes up but a sliver of the runtime, so don't think that would have any major impact
Simon Spoorendonk
@spoorendonk
need to do some optimizations I can see :)
Erik Hellsten
@erohe_gitlab
You bloody better don't beat me ;) I've spent too much time on this ^^
Simon Spoorendonk
@spoorendonk
Me too 😀
Simon Spoorendonk
@spoorendonk
boom. No optimizations yet. But now I can do callbacks to initialization, solution feasibility check, primal heuristic, and your very own pricing algorithm. Some docs and then a new version comming up
Erik Hellsten
@erohe_gitlab
Sweet As! The development of tomorrow is underway =) Good to hear!
Simon Spoorendonk
@spoorendonk
moved to github now. They support build on windows. Added you to my example project to see callback (and other) functionality. New version is available with the callbacks
Erik Hellsten
@erohe_gitlab
Ok, managed to download it. Though I didn't see the GitHub invite. Which account did you invite?
Simon Spoorendonk
@spoorendonk
@ErikOrm