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- Reformulation in the large:
- First stage of the project, mutual reformulations of the pure VRP
and JSP and application of the standard solving techniques:
- The second stage of the project, more efficient code:
- Default vehicle routing encoding
(ILOG Dispatcher 3.1, see ILOG Dispatcher 3.1 User's Manual); differs
from that above in particular modelling issues to do with
software version differences; includes a subclass extention
to the IloDistance standard class; the extention allows one
to specify distances between nodes as a matrix.
- Vehicle routing reformulated as
open shop (ILOG Scheduler 5.1); differences from the above
encoding include a more efficient way of dealing with capacities;
a clearer model; search made simpler;
- Job shop reformulated as
vehicle routing (for Dispatcher 3.1); a
better search procedure, iterative approach that consists in
setting a soft deadline and gradually improving it.
- The third stage of the project, a large-scale symmetric experimental study of
the influence of the conceptual differences between the VRP and job
shop. We start off from both pure VRP and JSP and varying one problem
parameter at a time move across the VRP-JSP continuum analysing
algorithmic performance:
- Reformulation in the small:
- Some examples to illustrate the usage of different concepts of
search a la ILOG Solver 5.x and Scheduler 5.x:
- Solver Example 1: shows how you could
specify value orderings, in the example random value ordering is
used, you could change it adjusting it to your needs;
- Solver Example 2: shows how you could
specify variable orderings, in the example shortest-domain-first
variable ordering is used, you could adjust it to your needs;
- Solver Example 3: shows how you could
specify both value & variable orderings at the same time;
- Scheduler Example: shows how
you could specify different resource allocation/scheduling
heuristics: interleaving allocation-sequencing phases using texture
measurements, random possible resource assignments (when a resource
constraint has a few alternative resources), min-number-of-possible-resources
choice of resource constraints. The code uses a data file test.dat, which is a 5x5 job shop
instance in a special format (see the readme file in the PRAS VRP/JSP Problem Instances
directory of the Resources section of
this site).
For code, also see the Resources tab of this page.
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