/**
* Constructor: build an STPG from an MDP. Data is copied directly from the MDP so take a copy
* first if you plan to keep/modify the MDP.
*/
public STPGAbstrSimple(MDPSimple m) {
DistributionSet set;
int i;
// TODO: actions?
initialise(m.getNumStates());
copyFrom(m);
for (i = 0; i < numStates; i++) {
set = newDistributionSet(null);
set.addAll(m.getChoices(i));
addDistributionSet(i, set);
}
}
@Override
public Iterator<Entry<Integer, Double>> getNestedTransitionsIterator(int s, int i, int j) {
DistributionSet ds = trans.get(s).get(i);
Iterator<Distribution> iter = ds.iterator();
Distribution distr = null;
int k = 0;
while (iter.hasNext() && k <= j) {
distr = iter.next();
k++;
}
if (k <= j) return null;
else return distr.iterator();
}
@Override
public int getNumNestedTransitions(int s, int i, int j) {
DistributionSet ds = trans.get(s).get(i);
Iterator<Distribution> iter = ds.iterator();
Distribution distr = null;
int k = 0;
while (iter.hasNext() && k <= j) {
distr = iter.next();
k++;
}
if (k <= j) return 0;
else return distr.size();
}
@Override
public void findDeadlocks(boolean fix) throws PrismException {
for (int i = 0; i < numStates; i++) {
// Note that no distributions is a deadlock, not an empty distribution
if (trans.get(i).isEmpty()) {
addDeadlockState(i);
if (fix) {
DistributionSet distrs = newDistributionSet(null);
Distribution distr = new Distribution();
distr.add(i, 1.0);
distrs.add(distr);
addDistributionSet(i, distrs);
}
}
}
}
@Override
public void clearState(int i) {
// Do nothing if state does not exist
if (i >= numStates || i < 0) return;
// Clear data structures and update stats
List<DistributionSet> list = trans.get(i);
numDistrSets -= list.size();
for (DistributionSet set : list) {
numDistrs -= set.size();
for (Distribution distr : set) numTransitions -= distr.size();
}
// TODO: recompute maxNumDistrSets
// TODO: recompute maxNumDistrs
// Remove all distribution sets
trans.set(i, new ArrayList<DistributionSet>(0));
}
/**
* Add distribution set 'newSet' to state s (which must exist). Distribution set is only actually
* added if it does not already exists for state s. (Assuming 'allowDupes' flag is not enabled.)
* Returns the index of the (existing or newly added) set. Returns -1 in case of error.
*/
public int addDistributionSet(int s, DistributionSet newSet) {
ArrayList<DistributionSet> set;
// Check state exists
if (s >= numStates || s < 0) return -1;
// Add distribution set (if new)
set = trans.get(s);
if (!allowDupes) {
int i = set.indexOf(newSet);
if (i != -1) return i;
}
set.add(newSet);
// Update stats
numDistrSets++;
maxNumDistrSets = Math.max(maxNumDistrSets, set.size());
numDistrs += newSet.size();
maxNumDistrs = Math.max(maxNumDistrs, newSet.size());
for (Distribution distr : newSet) numTransitions += distr.size();
return set.size() - 1;
}
/** Simple test program */
public static void main(String args[]) {
STPGModelChecker mc;
STPGAbstrSimple stpg;
DistributionSet set;
Distribution distr;
// ModelCheckerResult res;
BitSet target;
// Simple example: Create and solve the stochastic game from:
// Mark Kattenbelt, Marta Kwiatkowska, Gethin Norman, David Parker
// A Game-based Abstraction-Refinement Framework for Markov Decision Processes
// Formal Methods in System Design 36(3): 246-280, 2010
try {
// Build game
stpg = new STPGAbstrSimple();
stpg.addStates(4);
// State 0 (s_0)
set = stpg.newDistributionSet(null);
distr = new Distribution();
distr.set(1, 1.0);
set.add(distr);
stpg.addDistributionSet(0, set);
// State 1 (s_1,s_2,s_3)
set = stpg.newDistributionSet(null);
distr = new Distribution();
distr.set(2, 1.0);
set.add(distr);
distr = new Distribution();
distr.set(1, 1.0);
set.add(distr);
stpg.addDistributionSet(1, set);
set = stpg.newDistributionSet(null);
distr = new Distribution();
distr.set(2, 0.5);
distr.set(3, 0.5);
set.add(distr);
distr = new Distribution();
distr.set(3, 1.0);
set.add(distr);
stpg.addDistributionSet(1, set);
// State 2 (s_4,s_5)
set = stpg.newDistributionSet(null);
distr = new Distribution();
distr.set(2, 1.0);
set.add(distr);
stpg.addDistributionSet(2, set);
// State 3 (s_6)
set = stpg.newDistributionSet(null);
distr = new Distribution();
distr.set(3, 1.0);
set.add(distr);
stpg.addDistributionSet(3, set);
// Print game
System.out.println(stpg);
// Model check
mc = new STPGModelChecker(null);
// mc.setVerbosity(2);
target = new BitSet();
target.set(3);
stpg.exportToDotFile("stpg.dot", target);
System.out.println("min min: " + mc.computeReachProbs(stpg, target, true, true).soln[0]);
System.out.println("max min: " + mc.computeReachProbs(stpg, target, false, true).soln[0]);
System.out.println("min max: " + mc.computeReachProbs(stpg, target, true, false).soln[0]);
System.out.println("max max: " + mc.computeReachProbs(stpg, target, false, false).soln[0]);
} catch (PrismException e) {
System.out.println(e);
}
}
@Override
public void buildFromPrismExplicit(String filename) throws PrismException {
BufferedReader in;
Distribution distr;
DistributionSet distrs;
String s, ss[];
int i, j, k1, k2, iLast, k1Last, k2Last, n, lineNum = 0;
double prob;
try {
// Open file
in = new BufferedReader(new FileReader(new File(filename)));
// Parse first line to get num states
s = in.readLine();
lineNum = 1;
if (s == null) {
in.close();
throw new PrismException("Missing first line of .tra file");
}
ss = s.split(" ");
n = Integer.parseInt(ss[0]);
// Initialise
initialise(n);
// Go though list of transitions in file
iLast = -1;
k1Last = -1;
k2Last = -1;
distrs = null;
distr = null;
s = in.readLine();
lineNum++;
while (s != null) {
s = s.trim();
if (s.length() > 0) {
ss = s.split(" ");
i = Integer.parseInt(ss[0]);
k1 = Integer.parseInt(ss[1]);
k2 = Integer.parseInt(ss[2]);
j = Integer.parseInt(ss[3]);
prob = Double.parseDouble(ss[4]);
// For a new state or distribution set or distribution
if (i != iLast || k1 != k1Last || k2 != k2Last) {
// Add any previous distribution to the last set, create new one
if (distrs != null) {
distrs.add(distr);
}
distr = new Distribution();
// Only for a new state or distribution set...
if (i != iLast || k1 != k1Last) {
// Add any previous distribution set to the last state, create new one
if (distrs != null) {
addDistributionSet(iLast, distrs);
}
distrs = newDistributionSet(null);
}
}
// Add transition to the current distribution
distr.add(j, prob);
// Prepare for next iter
iLast = i;
k1Last = k1;
k2Last = k2;
}
s = in.readLine();
lineNum++;
}
// Add previous distribution to the last set
distrs.add(distr);
// Add previous distribution set to the last state
addDistributionSet(iLast, distrs);
// Close file
in.close();
} catch (IOException e) {
System.out.println(e);
System.exit(1);
} catch (NumberFormatException e) {
throw new PrismException("Problem in .tra file (line " + lineNum + ") for " + getModelType());
}
// Set initial state (assume 0)
initialStates.add(0);
}
