Shared Tools: Reference Manual
|Release Level || 5.4
||Release Date ||2008 10
||Revision Level ||1.0
Last modified on:
Monday, 20-Jul-09 14:05 CEST
DMC: discrete multi-criteria optimization
The DMC tool is an interactive discrete, multi criteria
optimization system, using a reference point approach and normalization
of the decision space between nadir and uotpia.
The sets of alternatives to analyze can either be:
- imported as a set from WRM optimization scenarios
(use the button: DMC" after a successful optimization run at
the optimization scenario overview level to export the feasible alternatives generated);
- imported individually from WRM model runs;
- imported from a CSV file (exported from a spreadsheet)
- created (and edited) manually.
The tool operates on named sets of alternatives.
Each alternative in an object that has a set of attributes or
criteria that define it. The set of critiera or dimensions
in decision space is the same for all alternatives within a set.
The user can select or deselect any one of the criteria (with a
minimum of two) for consideration or use in the analysis.
Every one of the criteria used is define in the
Knowledge Base (KB) associated with the tool.
For each of the criteria, there is
The main concepts used include:
- a (scalar) value defined
- an optimization strategy or direction (minimize, maximize, meet)
defined; the latter case is a shortcut for minimizing the deviation
in either direction from the reference, in this case,
by default the median of the distribution for that criterion
in the set.
- an (optional) contraint (upper or lower bound,
or normalised distance depending on the strategy or
direction of optimization) defined.
The results is the efficient point, which is the current solution
or the best nondominated alternative, nearest to the reference point.
- define the set, add and delete alternatives;
with every new alternative, NADIR and UTOPIA may change;
- define the criteria, select or deselect from consideration;
a good strategy is to start with two criteria only, and add critiera
one by one towards a more complex problem.
- introduce constraints on any of the criteria to limit the subset
of feasible alternatives to be considered;
- introduce a reference point different from its default (UTOPIA).
In addition to the graphical display of the set of alternatives
with different colors for the different types of alternatives
(NADIR (BLACK); infeasible (small dark GREY);
dominated (larger light GREY), PARETO (GREENE); current (BLUE);
efficient (YELLOW); and REFERENCE (RED), the tools shows either
- a summary of the optimisation scenario with the import and
- a tabular summary and editor interface for an individual alternative
selected from the main list of alternatives with the associated
scattergram of all alternatives, the current alternative marked;
- a tabular summary of the set with the associated scattergram;
- an enlarge scattergram;
- the statistics for an individual criterion with a histogram,
with the possibility to select a second criterion for a display
of a scatergram and correlation (covariance) estimate.
The set of criteria can, in principle,
be defined by the user interactively:
criteria can be deleted from the set, and new ones can be
defined in the KnowledgeBase with the KB Editor
and added with the RECONFIGURE button. These will be set to a value of undefined
for all existing alternatives, which the user then can edit.
the current set of criteria is pre-defined depending on the air quality model used.