Now it is a good time to illustrate other (than just moving
aspiration and/or reservation points by clicking a mouse)
possibilities of specification of preferences.
In every iteration one can use any combination of the following
actions for analysis of the problem:
- One can change a shape of a function by selecting
the Change a shape item from the Shape menu
(as shown in Figure 27) which
activates the dialog illustrated in Figure 28.
In this dialog, the NetRev criterion
has been stabilized.
The stabilized criterion has a shape illustrated on
Figure 29
(which, of course, can also be changed by clicking the mouse).
The dialog presented in Figure 28 provides a selection of
two types of a stabilized criterion: stab and stab_sym
which differ by the way in which the shape of the corresponding function
can be modified.
The stab_sym is used for a case, where a symmetric
CAF function is desired.
In this case, which is a typical one, modifications of the function
are done in such a way that symmetry is assured.
However, for some
criteria a non-symmetric shape may be
appropriate. This can be achieved by using the stab type.
Figure 27:
Activation of the dialog for changing shape of a function.
Figure 28:
Dialog for changing shape of a function.
Figure 29:
ISAAP window after changing shape of a function.
Figure 30:
Values set by the mouse displayed in the dialog for setting values from the keyboard.
Figure 31:
Dialog for setting values from the keyboard after modification of the target, aspiration and reservation values.
- The specification of the aspiration
and reservation levels with
the help of the mouse is very handy, but it does not result
in setting precise values.
This is usually acceptable, but the user can also set precisely
the values of aspiration and reservation
levels (and target values for
stabilized criteria)
by using the Values option.
This dialog is illustrated in Figures 30
and 31.
The first of these Figures contains values set with a mouse, whereas
the second one contains values specified from the keyboard
through the illustrated dialog.
The dialog allows for setting (for each criterion) either a pair
of reservation and aspiration values,
or a target value for
a stabilized criterion.
This dialog contains for a minimized or maximized criterion
static text with values of Utopia and
approximation of Nadir point components (denoted by U and
N, respectively).
For any type of a criterion the current value (denoted by V)
of a criterion is displayed as a static text.
The values are set (and the plots are updated accordingly) after
clicking on the Set button.
The dialog has to be closed by the Close button.
- New values of aspiration and reservation levels
for any criteria can be set by clicking the mouse near a point which
you want to move.
However, more advanced users may want to specify (in addition to the
pairs of aspiration
and reservation levels) the piece-wise linear
component achievement function. An example of such a function
is demonstrated in Figure 32.
One can add more segments to any achievement function
by selecting the Add a point item from the Shape menu.
After selecting this option, the background of the ISAAP window will
be changed from the default gray color to green and will remain
green until one of the following options from this menu will
be selected (other options also change the background color to
alert a user that he/she should restore the default action of the
mouse by selecting the Move a point item).
In this mode (indicated by the green background) each click of the mouse
results in adding (at the current location of the mouse pointer)
one point to the component achievement function.
Once enough points have been added
the Move a point should be selected from the Shape menu,
which results in switching back to the default mode of MCMA (in which
a click of the mouse results in moving the nearest point to the place
currently pointed at by the mouse).
Additional point(s) no longer needed for the definition of the piece-wise
linear functions can be removed by (temporarily) switching the mode by
selection of the Delete a point from the Shape menu.
In this mode (indicated by the red background) each click of the mouse
results in removing one point (closest to the current location of
the mouse pointer) of the component achievement function.
Figure 32 shows the results of actions corresponding
to the three dialogs explained above (selection of stabilized
criterion NetRev, setting via the dialog
target value15
for this criterion and aspiration and reservation
levels for the remaining criteria)
and selections of additional segments for the achievement functions
for criteria FoodAv and Land.
The changes of the preferences are aimed at the further improvement
of the criterion TotEro.
The solution corresponding to the preferences set as shown
in Figure 32 is illustrated in Figure 33.
We have indeed achieved an improvement for the TotEro criterion,
however, at the cost of considerable decrease of food production.
Figure 32:
Preferences for fourth iteration.
Figure 33:
Solution for the fourth iteration.
In our last iteration before the break let us try to increase the
food production without increasing erosion.
Most probably the only way to achieve this is to relax our expectations
for the revenue.
Figures 34 and 35 illustrate settings
of preferences and the corresponding solution, respectively.
Please note that the shape of the component achievement function
for the NetRev
criterion is not symmetric.
This corresponds well to the nature of this criterion because one
usually would like to have different shapes for values above and below
the target value16.
The last solution shows that it is indeed possible to considerably
increase the food production while keeping the erosion level at almost
the same level.
However, this can be achieved at the expense of a considerable drop
of revenue.
Figure 34:
Preferences for the fifth iteration.
Figure 35:
Solution for the fifth iteration.
- ...value15
- The target value is marked on the graph by a triangle.
- ...value16
- For some engineering applications a symmetric
shape of stabilized criterion is often more appropriate.
