Re: [boost] [graph] Proposal: Algorithm for the Shortest Path Problem with Resource Constraints

From: Michael Drexl (michael_at_[hidden])
Date: 2005-12-09 02:54:50

Thank you for your interest and your comments.

> For such hard problems there is an enormous design space (and an even
> bigger algorithm space) to be considered, so a good dose of genericity
> in the implementation would be appreciated (hopefully it comes with
> concepts?).

Hm, I don't know what exactly you would consider a "good dose of 
genericity", but it may well be that I have made some design decisions 
that you'll find too restrictive/not generic enough. I'll post the code 
I propose - after some re-naming and re-formatting and the like to 
comply with the Boost standards - to the sandbox vault, then you can see 
for yourself.

> Since it's NP-hard, it would be good to have also a reduction from
> some well-known NP-complete problem to SPPRC (for example graph
> colouring), which would be very useful for testing (using some
> established implementation for that NP-complete problem).

As for the testing, I use the algorithm as a subroutine in a solution 
procedure for the Vehicle Routing Problem (VRP), and I have an 
alternative exact solution procedure for the VRP. Both procedures 
consistently yield the same solutions.

Moreover, I've tested it against the BGL algorithms for the SPP without 
resource constraints (which is an SPPRC with one resource constraint 
with no upper bound on the consumption of this resource), and achieved 
the same results there, too.

Finally, I've solved Shortest Path Problems with Time Windows (two 
resources: cost and time) with my algorithm and with an MIP solver 
(CPLEX), and this gave correct results as well.

Regards,

Michael