// FILE. . . . . d:/hak/hlt/src/hlt/math/fuzzy/FuzzyAlgebra.java
// EDIT BY . . . Hassan Ait-Kaci
// ON MACHINE. . Hp-Zbook
// STARTED ON. . Sun May 6 08:23:47 2018
package hlt.math.fuzzy;
/**
* This class provides definitions for two dual fuzzy operations
* sup (∨) and inf (∧) on a
* pair of fuzzy values a and b. The arguments and the
* value returned are of type double, but if the arguments are
* in [0,1], then so is the value returned. However, the
* arguments' values are not checked. Unless redefined otherwise, these
* operations default respectively to Math.max and
* Math.min; i.e.,
*
*
* - a ∨ b = Math.max(a,b)
* - a ∧ b = Math.min(a,b)
*
*
* But this class also defines two other dual pairs of fuzzy operations:
* product (or probabilistic); i.e.,
*
*
* - a ∨ b = a + b - a*b
* - a ∧ b = a*b
*
*
* and lukasievicz (or luka); i.e.,
*
*
* - a ∨ b = Math.min(a+b,1)
* - a ∧ b = Math.max(0,a+b-1)
*
*
* which can be set with the method setFuzzyAlgebra(String)
* with argument "maxmin" (the default), "product", or
* "luka".
*
* @see FuzzyMatrix
*
* @version Last modified on Thu Mar 28 11:53:46 2019 by hak
* @author Hassan Aït-Kaci
* @copyright © by the author
*/
public class FuzzyAlgebra implements FuzzyOperations
{
static private final int maxmin = 0;
static private final int product = 1;
static private final int luka = 2;
static private int fuzzyAlgebra = maxmin;
/**
* Sets the current fuzzy algebra to the one corresponding to the
* given string. If no known fuzzy algebra corresponds to the
* string, this sets it to max/min and issues a warning.
*/
static public void setFuzzyAlgebra (String algebra)
{
fuzzyAlgebra = algebraKind(algebra);
System.out.println("Current fuzzy algebra set to: "+stringForm(fuzzyAlgebra));
}
static private String stringForm (int algebra)
{
switch (algebra)
{
case maxmin:
return "Max/Min";
case product:
return "Product (Probabilistic)";
case luka:
return "Lukasiewicz";
}
return "Max/Min";
}
/**
* Returns an int identifying the fuzzy algebra corresponding
* to the given kind string.
*/
static private int algebraKind (String kind)
{
switch (kind)
{
case "MaxMin": case "maxmin":
case "MinMax": case "minmax":
case "Default": case "default":
return maxmin;
case "Probabilistic": case "probabilistic":
case "Product": case "product":
return product;
case "Luka": case "luka":
case "Lukasiewicz": case "lukasiewicz":
return luka;
default:
System.err.println("Warning! Unsupported fuzzy algebra: " + kind + "; using default (\"MaxMin\")");
}
return maxmin;
}
/**
* Returns the supremum of the arguments in the current fuzzy algebra.
*/
public double sup (double left, double right)
{
switch (fuzzyAlgebra)
{
case product:
return left + right - left*right;
case luka:
return Math.min(left+right,1);
}
return Math.max(left,right);
}
/**
* Returns the infimum of the arguments in the current fuzzy algebra.
*/
public double inf (double left, double right)
{
switch (fuzzyAlgebra)
{
case product:
return left*right;
case luka:
return Math.max(0,left+right-1);
}
return Math.min(left,right);
}
}