Example: Utility Functions for Car Evaluation
=============================================

Consider the root :doc:`attribute <DEXiGlosAttr>` of the :doc:`Car
Evaluation Model <DEXiCar>`. According to the :doc:`tree of
attributes <DEXiCarTree>`, the root attribute CAR depends on two
lower-level attributes: PRICE and TECH.CHAR. Thus, the utility function
that corresponds to CAR maps all the combinations of values of PRICE and
TECH.CHAR. into the values of CAR (see the :doc:`scales <DEXiCarScale>`
of these attributes). The function is defined by the table shown below.

.. image:: images/CarFunct.png
   :alt: Car: Utility function

Interpretation
--------------

The attributes PRICE and TECH.CHAR. have three and four values,
respectively, so the number of rows in the table is 3×4=12. Each row
provides a value of CAR for one combination of the values of PRICE and
TECH.CHAR. Interpreted as an *elementary decision rule*, the fourth row,
for example, means the following:

**if** PRICE=medium **and** TECH.CHAR.=bad **then** CAR=unacc.

See also
--------

Representing this and other utility functions using :doc:`complex
rules <DEXiGlosComplex>`.

:doc:`All utility functions <DEXiCarFunct2>` defined in the :doc:`Car
Evaluation Model <DEXiCar>`.

:doc:`Options <DEXiCarEval>` evaluated in the :doc:`Car Evaluation
Model <DEXiCar>`.

.. toctree::
  :hidden:

  DEXiCarFunct2