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//==============================================================================
//
// Copyright (c) 2002-
// Authors:
// * Dave Parker <david.parker@comlab.ox.ac.uk> (University of Oxford)
//
//------------------------------------------------------------------------------
//
// This file is part of PRISM.
//
// PRISM is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// PRISM is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with PRISM; if not, write to the Free Software Foundation,
// Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
//
//==============================================================================
package explicit;
import java.util.*;
import java.util.Map.Entry;
import explicit.rewards.MCRewards;
import parser.State;
import parser.Values;
import prism.ModelType;
import prism.PrismException;
import prism.PrismNotSupportedException;
/**
* Simple explicit-state representation of a DTMC, constructed (implicitly) as the embedded DTMC of a CTMC.
* i.e. P(i,j) = R(i,j) / E(i) if E(i) > 0 and P(i,i) = 1 otherwise
* where E(i) is the exit rate for state i: sum_j R(i,j).
* This class is read-only: most of data is pointers to other model info.
*/
public class DTMCEmbeddedSimple extends DTMCExplicit
{
// Parent CTMC
protected CTMCSimple ctmc;
// Exit rates vector
protected double exitRates[];
// Number of extra transitions added (just for stats)
protected int numExtraTransitions;
/**
* Constructor: create from CTMC.
*/
public DTMCEmbeddedSimple(CTMCSimple ctmc)
{
this.ctmc = ctmc;
this.numStates = ctmc.getNumStates();
// TODO: should we copy other stuff across too?
exitRates = new double[numStates];
numExtraTransitions = 0;
for (int i = 0; i < numStates; i++) {
exitRates[i] = ctmc.getTransitions(i).sum();
if (exitRates[i] == 0)
numExtraTransitions++;
}
}
@Override
public void buildFromPrismExplicit(String filename) throws PrismException
{
throw new PrismNotSupportedException("Not supported");
}
// Accessors (for Model)
public ModelType getModelType()
{
return ModelType.DTMC;
}
public int getNumStates()
{
return ctmc.getNumStates();
}
public int getNumInitialStates()
{
return ctmc.getNumInitialStates();
}
public Iterable<Integer> getInitialStates()
{
return ctmc.getInitialStates();
}
public int getFirstInitialState()
{
return ctmc.getFirstInitialState();
}
public boolean isInitialState(int i)
{
return ctmc.isInitialState(i);
}
public boolean isDeadlockState(int i)
{
return ctmc.isDeadlockState(i);
}
public List<State> getStatesList()
{
return ctmc.getStatesList();
}
public Values getConstantValues()
{
return ctmc.getConstantValues();
}
public int getNumTransitions()
{
return ctmc.getNumTransitions() + numExtraTransitions;
}
@Override
public SuccessorsIterator getSuccessors(final int s)
{
if (exitRates[s] == 0) {
return SuccessorsIterator.fromSingleton(s);
} else {
return ctmc.getSuccessors(s);
}
}
public int getNumChoices(int s)
{
// Always 1 for a DTMC
return 1;
}
@Override
public BitSet getLabelStates(String name)
{
return ctmc.getLabelStates(name);
}
@Override
public boolean hasLabel(String name)
{
return ctmc.hasLabel(name);
}
@Override
public Set<String> getLabels()
{
return ctmc.getLabels();
}
@Override
public void addLabel(String name, BitSet states)
{
throw new RuntimeException("Can not add label to DTMCEmbeddedSimple");
}
public void findDeadlocks(boolean fix) throws PrismException
{
// No deadlocks by definition
}
public void checkForDeadlocks() throws PrismException
{
// No deadlocks by definition
}
public void checkForDeadlocks(BitSet except) throws PrismException
{
// No deadlocks by definition
}
@Override
public String infoString()
{
String s = "";
s += numStates + " states (" + getNumInitialStates() + " initial)";
s += ", " + getNumTransitions() + " transitions (incl. " + numExtraTransitions + " self-loops)";
return s;
}
@Override
public String infoStringTable()
{
String s = "";
s += "States: " + numStates + " (" + getNumInitialStates() + " initial)\n";
s += "Transitions: " + getNumTransitions() + "\n";
return s;
}
// Accessors (for DTMC)
public int getNumTransitions(int s)
{
if (exitRates[s] == 0) {
return 1;
} else {
return ctmc.getNumTransitions(s);
}
}
public Iterator<Entry<Integer,Double>> getTransitionsIterator(int s)
{
if (exitRates[s] == 0) {
// return prob-1 self-loop
return Collections.singletonMap(s, 1.0).entrySet().iterator();
} else {
final Iterator<Entry<Integer,Double>> ctmcIterator = ctmc.getTransitionsIterator(s);
// return iterator over entries, with probabilities divided by exitRates[s]
final double er = exitRates[s];
return new Iterator<Entry<Integer,Double>>() {
@Override
public boolean hasNext()
{
return ctmcIterator.hasNext();
}
@Override
public Entry<Integer, Double> next()
{
final Entry<Integer, Double> ctmcEntry = ctmcIterator.next();
return new Entry<Integer, Double>() {
@Override
public Integer getKey()
{
return ctmcEntry.getKey();
}
@Override
public Double getValue()
{
return ctmcEntry.getValue() / er;
}
@Override
public Double setValue(Double value)
{
throw new UnsupportedOperationException();
}
};
}
};
}
}
@Override
public void forEachTransition(int s, TransitionConsumer c)
{
final double er = exitRates[s];
if (er == 0) {
// exit rate = 0 -> prob 1 self loop
c.accept(s, s, 1.0);
} else {
ctmc.forEachTransition(s, (s_,t,rate) -> {
c.accept(s_, t, rate / er);
});
}
}
public double mvMultSingle(int s, double vect[])
{
int k;
double d, er, prob;
Distribution distr;
distr = ctmc.getTransitions(s);
d = 0.0;
er = exitRates[s];
// Exit rate 0: prob 1 self-loop
if (er == 0) {
d += vect[s];
}
// Exit rate > 0
else {
for (Map.Entry<Integer, Double> e : distr) {
k = (Integer) e.getKey();
prob = (Double) e.getValue();
d += prob * vect[k];
}
d /= er;
}
return d;
}
@Override
public double mvMultJacSingle(int s, double vect[])
{
int k;
double diag, d, er, prob;
Distribution distr;
distr = ctmc.getTransitions(s);
diag = d = 0.0;
er = exitRates[s];
// Exit rate 0: prob 1 self-loop
if (er == 0) {
return 0.0;
}
// Exit rate > 0
else {
// (sum_{j!=s} P(s,j)*vect[j]) / (1-P(s,s))
// = (sum_{j!=s} (R(s,j)/E(s))*vect[j]) / (1-(P(s,s)/E(s)))
// = (sum_{j!=s} R(s,j)*vect[j]) / (E(s)-P(s,s))
for (Map.Entry<Integer, Double> e : distr) {
k = (Integer) e.getKey();
prob = (Double) e.getValue();
// Non-diagonal entries only
if (k != s) {
d += prob * vect[k];
} else {
diag = prob;
}
}
d /= (er - diag);
}
return d;
}
public double mvMultRewSingle(int s, double vect[], MCRewards mcRewards)
{
int k;
double d, er, prob;
Distribution distr;
distr = ctmc.getTransitions(s);
er = exitRates[s];
d = 0;
// Exit rate 0: prob 1 self-loop
if (er == 0) {
d += vect[s];
}
// Exit rate > 0
else {
for (Map.Entry<Integer, Double> e : distr) {
k = (Integer) e.getKey();
prob = (Double) e.getValue();
d += prob * vect[k];
}
d /= er;
}
d += mcRewards.getStateReward(s);
return d;
}
//@Override
public double mvMultRewJacSingle(int s, double vect[], MCRewards mcRewards)
{
int k;
double diag, d, er, prob;
Distribution distr;
distr = ctmc.getTransitions(s);
diag = d = 0.0;
er = exitRates[s];
// Exit rate 0: prob 1 self-loop
if (er == 0) {
return mcRewards.getStateReward(s);
}
// Exit rate > 0
else {
// (rew(s) + sum_{j!=s} P(s,j)*vect[j]) / (1-P(s,s))
// = (rew(s) + sum_{j!=s} (R(s,j)/E(s))*vect[j]) / (1-(P(s,s)/E(s)))
// = (E(s)*rew(s) + sum_{j!=s} R(s,j)*vect[j]) / (E(s)-P(s,s))
d = er * mcRewards.getStateReward(s);
for (Map.Entry<Integer, Double> e : distr) {
k = (Integer) e.getKey();
prob = (Double) e.getValue();
// Non-diagonal entries only
if (k != s) {
d += prob * vect[k];
} else {
diag = prob;
}
}
d /= (er - diag);
}
return d;
}
@Override
public void vmMult(double vect[], double result[])
{
// Initialise result to 0
Arrays.fill(result, 0);
// Go through matrix elements (by row)
for (int state = 0; state < numStates; state++) {
double er = exitRates[state];
// Exit rate 0: prob 1 self-loop
if (er == 0) {
result[state] += vect[state];
continue;
}
// Exit rate > 0
for (Iterator<Entry<Integer, Double>> transitions = ctmc.getTransitionsIterator(state); transitions.hasNext();) {
Entry<Integer, Double> trans = transitions.next();
int target = trans.getKey();
double prob = trans.getValue() / er;
result[target] += prob * vect[state];
}
}
}
@Override
public String toString()
{
int i, numStates;
boolean first;
String s = "";
s += "ctmc: " + ctmc;
first = true;
s = ", exitRates: [ ";
numStates = getNumStates();
for (i = 0; i < numStates; i++) {
if (first)
first = false;
else
s += ", ";
s += i + ": " + exitRates[i];
}
s += " ]";
return s;
}
@Override
public boolean equals(Object o)
{
if (o == null || !(o instanceof DTMCEmbeddedSimple))
return false;
DTMCEmbeddedSimple dtmc = (DTMCEmbeddedSimple) o;
if (!ctmc.equals(dtmc.ctmc))
return false;
if (!exitRates.equals(dtmc.exitRates))
return false;
if (numExtraTransitions != dtmc.numExtraTransitions)
return false;
return true;
}
}