123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400401402403404405406407408409410411412413414415416417418419420421422423424425426427428429430431432433434435436437438439440441442443444445446447448449450451452453454455456457458459460461462463464465466467468469470471472473474475476477478479480481482483484485486487488489490491492493494495496497498499500501502503504505506507508509510511512513514515516517518519520521522523524525526527528529530531532533534535536537538539540541542543544545546547548549550551552553554555556557558559560561562563564565566567568569570571572573574575576577578579580581582583584585586587588589590591592593594595596597598599600601602603604605606607608609610611612613614615616617618619620621622623624625626627628629630631632633634635636637638639640641642643644645646647648649650651652653654655656657658659660661662663664665666667668669670671672673674675676677678679680681682683684685686687688689690691692693694695696697698699700701702703704705706707708709710711712713714715716717718719720721722723724725726727728729730731732733734735736737738739740741742743744745746747748749750751752753754755756757758759760761762763764765766767768769770771772773774775776777778779780781782783784785786787788789790791792793794795796797798799800801802803804805806807808 |
- /**
- * CertainTrust SDK
- *
- * Implements the computational trust model "CertainTrust"
- * in Java.
- * See <http://www.tk.informatik.tu-darmstadt.de/de/research/smart-security-and-trust/> for further details.
- *
- *
- * Telecooperation Department, Technische Universit�t Darmstadt
- * <http://www.tk.informatik.tu-darmstadt.de/>
- *
- * Prof. Dr. Max Mühlhäuser <max@informatik.tu-darmstadt.de>
- * Florian Volk <florian.volk@cased.de>
- *
- *
- * @author Maria Pelevina
- * @author David Kalnischkies
- * @version 1.1
- */
- /* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
- package CertainTrust;
- import java.util.Observable;
- /**
- *
- * t - average rating value, [0; 1], from very negative to very positive
- * c - certainty value, [0; 1] from low certainty (no evidence) to the maximal maximal certainty.
- * f - initial trust value
- * w - weight
- * r - number of positive evidence
- * s - number of negative evidence
- * n - maximal number of expected evidence
- * doc - degree of conflict
- *
- */
- public class CertainTrust extends Observable {
-
- private double c, t, f, r, s, doc;
- private String name;
- private int n, weight = 2;
- //=========== Constructors =================
- /**
- * Constructs a CertainTrust object with predefined n value.
- * @param n - maximal number of expected evidence
- */
- public CertainTrust(int n) {
- if (n > 0) {
- this.n = n;
- c = 0;
- t = 0.5;
- f = 0.5;
- r = 0;
- s = 0;
- }
- else throw new IllegalArgumentException("N should be greater than 0. Entered n = " + n + "\n");
- }
-
- /**
- * Constructs a CertainTrust object with predefined r, s, n values.
- * @param r - number of positive evidence
- * @param s - number of negative evidence
- * @param n - maximal number of expected evidence
- */
- public CertainTrust(double r, double s, int n) {
- if (n > 0) {
- this.n = n;
- this.c = 0;
- this.t = 0.5;
- this.f = 0.5;
- this.doc = 0;
- setRS(r, s);
- }
- else throw new IllegalArgumentException("N should be greater than 0. Entered n = " + n + "\n");
- }
-
- /**
- * Constructs a CertainTrust object with predefined c, t, f, n values.
- * @param c - certainty
- * @param t - average rating
- * @param f - initial trust value
- * @param n - maximal number of expected evidence
- */
- public CertainTrust(double t, double c, double f, int n) {
- this(t,c,f,n,0);
- }
-
- /**
- * Constructs a CertainTrust object with predefined c, t, f, n values.
- * @param c - certainty
- * @param t - average rating
- * @param f - initial trust value
- * @param n - maximal number of expected evidence
- * @param doc - initial degree of conflict
- */
- private CertainTrust(double t, double c, double f, int n, double doc) {
- if (n > 0) {
- if (f <= 1 && f >= 0) {
- this.n = n;
- this.f = f;
- this.r = 0;
- this.s = 0;
- this.doc = doc;
- setTC(t, c);
- }
- else throw new IllegalArgumentException("f should lie within [0;1]. Entered f = " + f + "\n");
- }
- else throw new IllegalArgumentException("N should be greater than 0. Entered n = " + n + "\n");
- }
-
- //=========== Setters =================
- /**
- * Resets N value. Renormalises r and s values, recalculates c and t accordingly.
- * @param n - new maximal number of expected evidence
- */
- public void setN(int n) {
- if (n > 0) {
- this.n = n;
- normaliseRS();
- calculateRStoTC();
-
- setChanged();
- notifyObservers();
- }
- else throw new IllegalArgumentException("N should be greater than 0. Entered n = " + n + "\n");
- }
-
- /**
- * Sets f value.
- * @param f - initial trust value.
- */
- public void setF(double f) {
- if (f >= 0 && f <= 1) {
- this.f = f;
-
- setChanged();
- notifyObservers();
- }
-
- else throw new IllegalArgumentException("f should lie within [0;1]. Entered f = " + f + "\n");
- }
- /**
- * Sets Distance of Conflict value.
- * @param doc is the new value for DoC
- */
- public void setDoC(double doc) {
- if (doc > 0) {
- this.doc = doc;
- }
- else throw new IllegalArgumentException("DoC should be greater than 0. Entered DoC = " + doc + "\n");
- }
-
- /**
- * Sets c and t values. Recalculates r and s values accordingly.
- * @param t - new average trust value
- * @param c - new certainty value
- */
- public void setTC(double t, double c) {
- if (c >= 0 && c <= 1) {
- if (t >= 0 && t <= 1) {
- this.c = c;
- this.t = t;
- calculateTCtoRS();
-
- setChanged();
- notifyObservers();
- }
- else throw new IllegalArgumentException("t should be greater than 0. Entered t = " + t + "\n");
- }
- else throw new IllegalArgumentException("c should lie within [0;1]. Entered c = " + c + "\n");
- }
- /**
- * Sets r and s values. Recalculates c and t values accordingly.
- * @param r - new number of positive evidence
- * @param s - new number of negative evidence
- */
- public void setRS(double r, double s) {
- if (r >= 0) {
- if (s >= 0) {
- this.r = r;
- this.s = s;
- normaliseRS();
- calculateRStoTC();
-
- setChanged();
- notifyObservers();
- }
- else throw new IllegalArgumentException("s should be positive. Entered s = " + s + "\n");
- }
- else throw new IllegalArgumentException("r should be positive. Entered r = " + r + "\n");
- }
-
- /**
- * Sets name value.
- * @param name - name of object.
- */
- public void setName(String s) {
- this.name = s;
- }
-
- /**
- * Add some positive evidence to r.
- * @param posEvidence - number of new positive evidences
- */
- public void addR(int posEvidence) {
- if (posEvidence >= 0) {
- r += posEvidence;
- normaliseRS();
- calculateRStoTC();
-
- setChanged();
- notifyObservers();
- }
- else throw new IllegalArgumentException("Number of positive evidences should be positive. Entered " + posEvidence + "\n");
- }
-
- /**
- * Add some negative evidence to s.
- * @param negEvidence - number of new negative evidences
- */
- public void addS(int negEvidence) {
- if (negEvidence >= 0) {
- s += negEvidence;
- normaliseRS();
- calculateRStoTC();
-
- setChanged();
- notifyObservers();
- }
- else throw new IllegalArgumentException("Number of negative evidences should be positive. Entered " + negEvidence + "\n");
- }
-
- //=========== Internal Calculations ==========
- /**
- * Normalises r and s values according to n - maximal number of expected evidence
- * Important! Doesn't notify observers.
- */
- private void normaliseRS() {
- if (r + s > n){
- double initR = r;
- r = r*n / (initR + s);
- s = s*n / (initR + s);
- }
- }
- /**
- * Calculates c and t values based on existing r and s values
- * Important! Doesn't notify observers.
- */
- private void calculateRStoTC() {
- c = n * (r + s) / ( weight*(n-r-s) + n*(r+s));
- if (c == 0)
- t = 0.5;
- else t = r / (r + s);
- }
-
- /**
- * Calculates r and s values based on existing c and t values
- * Important! Doesn't notify observers.
- */
- private void calculateTCtoRS() {
- if (c == 0) {
- r = 0;
- s = 0;
- t = 0.5;
- }
- else {
- r = (2*c*weight*n*t) / (2*c*weight + n - c*n);
- s = (2*c*weight*n - 2*c*weight*n*t) / (2*c*weight + n - c*n);
- }
- }
-
- //=========== Getters =================
- public double getC() {
- return c;
- }
- public double getT() {
- return t;
- }
- public double getF() {
- return f;
- }
- public double getR() {
- return r;
- }
- public double getS() {
- return s;
- }
- public int getN() {
- return n;
- }
-
- public double getDoC() {
- return doc;
- }
-
- public String getName() {
- return name;
- }
-
- public double getExpectation() {
- return t*c + (1-c)*f;
- }
-
- //=========== Logic =================
- /**
- * Computes OR function for this CertainTrust object and the specified argument. Result is returned as a new object,
- * argument and this CertainTrust object remain unchanged.
- * N values of both objects should be equal.
- * For detailed information see CertainLogic: A Logic for Modeling Trust and Uncertainty
- * @param arg - CertainTrust object
- * @return - result of OR computation for this object and an argument.
- */
-
- private CertainTrust OR(CertainTrust arg){
- double c1 = getC();
- double t1 = getT();
- double f1 = getF();
-
- double c2 = arg.getC();
- double t2 = arg.getT();
- double f2 = arg.getF();
-
- double resT = 0.5, resF = 0.5, resC = 0;
-
- if (this.getN() != arg.getN())
- throw new IllegalStateException("Different N values. Operation not allowed. \n");
-
- resF = f1 + f2 - f1*f2;
- if (almostEqual(resF, 0)) { //--------Modified by Debashis----------------//
- f1 = 0.99999;
- f2 = 0.99999;
- resF = f1 + f2 - f1*f2;
- resC = c1 + c2 - c1*c2- (c1*f2*(1-c2)*(1-t1)+c2*f1*(1-c1)*(1-t2)) / resF;
- }
- else
- resC = c1 + c2 - c1*c2 - (c1*f2*(1-c2)*(1-t1)+c2*f1*(1-c1)*(1-t2)) / resF;
-
- if (almostEqual(resC, 0))
- resT = 0.5;
- else resT = (1/resC) * (c1*t1 + c2*t2 - c1*c2*t1*t2);
-
- resT = adjustValue(resT);
- resC = adjustValue(resC);
- resF = adjustValue(resF);
-
- CertainTrust result = new CertainTrust(resT, resC, resF, n, 0);
-
- return result;
- }
- /**
- * Computes OR function for this CertainTrust object and the specified arguments.
- * Result is returned as a new object, arguments and this CertainTrust object remain unchanged.
- * Example: a.OR(b, c, d) returns new CertainTrust object that equals a OR b OR c OR d.
- * Multiple arguments allowed, but not less than one.
- * N values of all objects should be equal.
- * For detailed information see CertainLogic: A Logic for Modeling Trust and Uncertainty
- * @param args - arguments
- * @return - result of OR computation for this object and all arguments.
- */
- public CertainTrust OR(CertainTrust ...args) {
- CertainTrust result = clone();
- for (CertainTrust m: args) {
- if (n != m.getN())
- throw new IllegalStateException("Different N values. Operation not allowed. \n");
- result = result.OR(m);
- }
-
- return result;
- }
-
- /**
- * Computes AND function for this CertainTrust object and the specified argument. Result is returned as a new object,
- * argument and this CertainTrust object remain unchanged.
- * N values of both objects should be equal.
- * For detailed information see CertainLogic: A Logic for Modeling Trust and Uncertainty
- * @param arg - CertainTrust object
- * @return - result of AND computation for this object and an argument.
- */
- private CertainTrust AND(CertainTrust arg){
- double c1 = getC();
- double f1 = getF();
- double t1 = getT();
-
- double c2 = arg.getC();
- double f2 = arg.getF();
- double t2 = arg.getT();
-
- double resC = 0, resT = 0.5, resF = 0.5;
-
- if (n != arg.getN())
- throw new IllegalStateException("Different N values. Operation not allowed. \n");
-
- resF = f1*f2;
-
- if (almostEqual(resF, 1)) { //--------Modified by Debashis----------------//
- f1 = 0.99999;
- f2 = 0.99999;
- resF = f1*f2;
- resC = c1 + c2 - c1*c2- (c2*t2*(1-c1)*(1-f1)+c1*t1*(1-c2)*(1-f2)) / (1 - resF);
- }
- else
- resC = c1 + c2 - c1*c2 - (c2*t2*(1-c1)*(1-f1)+c1*t1*(1-c2)*(1-f2)) / (1 - resF);
-
- if (almostEqual(resC, 0))
- resT = 0.5;
- else if (almostEqual(resF, 1)) //avoid division by 0
- resT = (1/resC) * (c1*t1*c2*t2);
- else resT = (1/resC) * ((c1*t1*c2*t2) + (c1*f2*t1*(1-c2)*(1-f1)+c2*f1*t2*(1-c1)*(1-f2)) / (1 - resF));
-
- resT = adjustValue(resT);
- resC = adjustValue(resC);
- resF = adjustValue(resF);
-
- CertainTrust result = new CertainTrust(resT, resC, resF, n, 0);
-
- return result;
- }
-
- /**
- * Computes AND function for this CertainTrust object and the specified arguments.
- * Result is returned as a new object, arguments and this CertainTrust object remain unchanged.
- * Example: a.AND(b, c, d) returns new CertainTrust object that equals a AND b AND c AND d.
- * Multiple arguments allowed, but not less than one.
- * N values of all objects should be equal.
- * For detailed information see CertainLogic: A Logic for Modeling Trust and Uncertainty
- * @param args - arguments
- * @return - result of AND computation for this object and all arguments.
- */
- public CertainTrust AND(CertainTrust ...args) {
- CertainTrust result = clone();
- for (CertainTrust m: args) {
- if (n != m.getN())
- throw new IllegalStateException("Different N values. Operation not allowed. \n");
- result = result.AND(m);
- }
-
- return result;
- }
-
- /**
- * Returns NOT of this CertainTrust object.
- * For detailed information see CertainLogic: A Logic for Modeling Trust and Uncertainty
- * @return - NOT of this CertainTrust object.
- */
- public CertainTrust NOT(){
- return new CertainTrust(getC(), adjustValue(1 - getT()), adjustValue(1 - getF()), n, 0);
- }
-
- /**
- * an internal implementation of fusion function.
- * Is called by wFusion and cFusion
- * @param args - an array of CertainTrust objects
- * @param weights - an integer array of corresponding weights
- * @param doc - a degree of conflict (always 0 for wFusion)
- * @return - new CertainTrust object
- */
- private static CertainTrust internalFusion(CertainTrust[] args, int[] weights, double doc) {
- double resC, resT, resF;
- boolean allOne = true;
- boolean allZero = true;
- boolean allWeightsZero = true;
- boolean atLeastOne1 = false;
- int arrLength = args.length;
-
- // set the flags about C and Weight values
- for (int i = 0; i < arrLength; i++)
- if (args[i].getC() != 1) {
- allOne = false;
- i = arrLength;
- }
- for (int i = 0; i < arrLength; i++)
- if (args[i].getC() != 0) {
- allZero = false;
- i = arrLength;
- }
- for (int i = 0; i < arrLength; i++)
- if (weights[i] != 0) {
- allWeightsZero = false;
- i = arrLength;
- }
- for (int i = 0; i < arrLength; i++)
- if (args[i].getC() == 1) {
- atLeastOne1 = true;
- i = arrLength;
- }
-
- //-------------Modified by Debashis-----------------//
- if(atLeastOne1 && !allOne){
- for (int i = 0; i < arrLength; ++i)
- if (args[i].getC() == 1) {
- args[i].setTC(args[i].getT(),0.99999);
- }
- }
-
- //Calculate T and C
-
- // 1. all C's = 1
- if (allOne) {
- // set C
- resC = 1 * (1 - doc);
- // set T
- if (allWeightsZero) {// save some calculation time
- resT = 0;
- }
- else { // or use the function
- double numeratorT = 0, denominatorT = 0;
- for (int i = 0; i < arrLength; i++) {
- numeratorT += weights[i] * args[i].getT();
- denominatorT += weights[i];
- }
- resT = numeratorT/denominatorT;
- }
- }
-
- else {
- if (atLeastOne1)
- throw new IllegalStateException("Illeagal arguments. Either all C values must equal 1 or none of them. Operation not allowed \n");
- // 2. Any other combination
- if (allWeightsZero) { // save some calculation time
- resT = 0;
- resC = 0;
- }
- else { // or use the function
- double numeratorT = 0, denominatorT = 0, numeratorC = 0, denominatorC = 0, mult;
- for (int i = 0; i < arrLength; i++) {
- mult = 1;
- for (int j = 0; j < arrLength; j++) // Count the product for each sum element
- if (j != i)
- mult *= 1 - args[j].getC();
- numeratorT += weights[i] * args[i].getT() * args[i].getC() * mult;
- denominatorT += weights[i] * args[i].getC() * mult;
- denominatorC += weights[i] * mult;
- }
- numeratorC = denominatorT;
- resC = (numeratorC/denominatorC) * (1 - doc);
- if (allZero)
- resT = 0.5;
- else
- resT = numeratorT/denominatorT;
- }
-
- // Special case for T
- if (allZero)
- resT = 0.5;
- }
-
- // Calculate F
- if (allWeightsZero)
- resF = 0;
- else {
- double numerator = 0, denominator = 0;
- for (int i = 0; i < arrLength; i ++) {
- numerator += weights[i] * args[i].getF();
- denominator += weights[i];
- }
- resF = numerator/denominator;
- }
- return new CertainTrust(resT, resC, resF, args[0].getN(), doc);
- }
-
- /**
- * Performs weighted fusion for an array of CertainTrust objects in correspondence with
- * an array of weights. Returns new CertainTrust object.
- * Requirements: N values of CertainTrust objects must be equal.
- * Number of weights should equal the number of CertainTrust objects.
- * Arrays must be non-empty
- * Either all of CertainTrust must be of certainty 1 or none of them.
- * @param args - an array of CertainTrust objects
- * @param weights - an integer array of corresponding weights
- * @return - new CertainTrust object
- */
- public static CertainTrust wFusion(CertainTrust[] args, int[] weights) {
- //arrays should be equal
- if (args.length == weights.length) {
- //and not empty
- if (args.length != 0) {
- boolean equalNs = true;
- int N = args[0].getN();
- for (int i = 1; i < args.length; i++)
- if (N != args[i].getN()) {
- equalNs = false;
- i = args.length;
- }
- //and all N's of TC's must be equal
- if (equalNs) {
- return internalFusion(args, weights, 0);
- }
- throw new IllegalStateException("Different N values. Operation not allowed. \n");
- }
- throw new IllegalStateException("Arrays are empty. Operation not allowed. \n");
- }
- throw new IllegalStateException("Different lengths of arrays. Operation not allowed. \n");
- }
-
- /**
- * Conflicted Fusion is a variation of weighted fusion, which additionally computes the degree of conflict
- * between given opinions (CertainTrust objects) and takes it into consideration while performing fusion.
- * The degree of conflict is then saved in the resulting CertainTrust object and may be checked with getDoC() function.
- * @param args - an array of CertainTrust objects
- * @param weights - an integer array of corresponding weights
- * @return - new CertainTrust object
- */
- public static CertainTrust cFusion(CertainTrust[] args, int[] weights) {
- //arrays should be equal
- if (args.length == weights.length) {
- //and not empty
- if (args.length != 0) {
- boolean equalNs = true;
- int N = args[0].getN();
- for (int i = 1; i < args.length; i++)
- if (N != args[i].getN()) {
- equalNs = false;
- i = args.length;
- }
- //and all N's of TC's must be equal
- if (equalNs) {
- double denominator = args.length*(args.length - 1) / 2;
- double numerator = 0;
- for (int i = 0; i < args.length; i++)
- for (int j = i; j < args.length; j++)
- numerator += Math.abs(args[i].getT() - args[j].getT()) * args[i].getC() * args[j].getC()*(1 - Math.abs((double)(weights[i] - weights[j])/(weights[i] + weights[j])));
- double doc = numerator/denominator;
- return internalFusion(args, weights, doc);
- }
- throw new IllegalStateException("Different N values. Operation not allowed. \n");
- }
- throw new IllegalStateException("Arrays are empty. Operation not allowed. \n");
- }
- throw new IllegalStateException("Different lengths of arrays. Operation not allowed. \n");
- }
-
- /**
- * Computes CONSENSUS function for this CertainTrust object and the specified argument. Result is returned as a new object,
- * argument and this CertainTrust object remain unchanged.
- * N values of both objects should be equal.
- * For detailed information see CertainLogic: A Logic for Modeling Trust and Uncertainty
- * @param arg - CertainTrust object
- * @return - result of CONSENSUS computation for this object and an argument.
- */
- private CertainTrust CONSENSUS(CertainTrust arg){
- double c1 = getC();
- double f1 = getF();
- double t1 = getT();
-
- double c2 = arg.getC();
- double f2 = arg.getF();
- double t2 = arg.getT();
-
- double resC = 0, resT = 0.5, resF = 0.5;
-
- if (n != arg.getN())
- throw new IllegalStateException("Different N values. Operation not allowed. \n");
-
- double tempC = c1*c2;
- if (this.almostEqual(tempC, 1)){ //avoid division by 0
- c1 = 0.99999;
- c2 = 0.99999;
- }
-
- resF = (f1*c1*(1-c2) + f2*c2*(1-c1))/(c1+c2-2*c1*c2);
- resC = (c1+c2-2*c1*c2)/(1-c1*c2);
- resT = (c1*t1*(1-c2)+c2*t2*(1-c1))/(c1+c2-2*c1*c2);
-
- resT = adjustValue(resT);
- resC = adjustValue(resC);
- resF = adjustValue(resF);
-
- CertainTrust result = new CertainTrust(resT, resC, resF, n, 0);
-
- return result;
- }
-
- /**
- * Computes CONSENSUS function for this CertainTrust object and the specified arguments.
- * Result is returned as a new object, arguments and this CertainTrust object remain unchanged.
- * Example: a.CONSENSUS(b, c, d) returns new CertainTrust object that equals a CONSENSUS b CONSENSUS c CONSENSUS d.
- * Multiple arguments allowed, but not less than one.
- * N values of all objects should be equal.
- * For detailed information see CertainLogic: A Logic for Modeling Trust and Uncertainty
- * @param args - arguments
- * @return - result of CONSENSUS computation for this object and all arguments.
- */
- public CertainTrust CONSENSUS(CertainTrust ...args) {
- CertainTrust result = clone();
- for (CertainTrust m: args) {
- if (n != m.getN())
- throw new IllegalStateException("Different N values. Operation not allowed. \n");
- result = result.CONSENSUS(m);
- }
-
- return result;
- }
- /**
- * Computes DISCOUNTING function for this CertainTrust object and the specified argument. Result is returned as a new object,
- * argument and this CertainTrust object remain unchanged.
- * N values of both objects should be equal.
- * For detailed information see CertainLogic: A Logic for Modeling Trust and Uncertainty
- * @param arg - CertainTrust object
- * @return - result of DISCOUNTING computation for this object and an argument.
- */
- private CertainTrust DISCOUNTING(CertainTrust arg){
- double c1 = getC();
- double f1 = getF();
- double t1 = getT();
-
- double c2 = arg.getC();
- double f2 = arg.getF();
- double t2 = arg.getT();
-
- double resC = 0, resT = 0.5, resF = 0.5;
-
- if (n != arg.getN())
- throw new IllegalStateException("Different N values. Operation not allowed. \n");
-
- resF = f2;
-
- if (almostEqual(resF, 1))
- resC = t1*c1*c2;
- else
- resC = t1*c1*c2;
-
- if (almostEqual(resC, 0))
- resT = 0.5;
- else if (almostEqual(resF, 1))
- resT = t2;
- else resT = t2;
-
- resT = adjustValue(resT);
- resC = adjustValue(resC);
- resF = adjustValue(resF);
-
- CertainTrust result = new CertainTrust(resT, resC, resF, n, 0);
-
- return result;
- }
-
- /**
- * Computes DISCOUNTING function for this CertainTrust object and the specified arguments.
- * Result is returned as a new object, arguments and this CertainTrust object remain unchanged.
- * Example: a.DISCOUNTING(b, c, d) returns new CertainTrust object that equals a DISCOUNTING b DISCOUNTING c DISCOUNTING d.
- * Multiple arguments allowed, but not less than one.
- * N values of all objects should be equal.
- * For detailed information see CertainLogic: A Logic for Modeling Trust and Uncertainty
- * @param args - arguments
- * @return - result of DISCOUNTING computation for this object and all arguments.
- */
- public CertainTrust DISCOUNTING(CertainTrust ...args) {
- CertainTrust result = clone();
- for (CertainTrust m: args) {
- if (n != m.getN())
- throw new IllegalStateException("Different N values. Operation not allowed. \n");
- result = result.DISCOUNTING(m);
- }
-
- return result;
- }
-
-
- //=========== Additional Functions =================
-
- @Override
- public CertainTrust clone() {
- CertainTrust copy = new CertainTrust(n);
- copy.c = this.c;
- copy.t = this.t;
- copy.f = this.f;
- copy.r = this.r;
- copy.s = this.s;
- copy.doc = this.doc;
- return copy;
- }
-
- /**
- * Adjusts the value of a into the allowed range [0,1].
- * @param a - value to be adjusted
- */
- private double adjustValue(double a) {
- return Math.max(Math.min(a, 1), 0);
- }
-
- /**
- * compares two double values using an epsilon
- * @param value - given value
- * @param target - expected value
- * @return
- */
- private boolean almostEqual(double value, double target) {
- return Math.abs(value - target) < 1E-10;
- }
- }
|