protected StateValues checkProbBoundedUntil(Model model, ExpressionTemporal expr, boolean min)
throws PrismException {
double uTime;
BitSet b1, b2;
StateValues probs = null;
ModelCheckerResult res = null;
// get info from bounded until
uTime = expr.getUpperBound().evaluateDouble(constantValues);
if (uTime < 0 || (uTime == 0 && expr.upperBoundIsStrict())) {
String bound = (expr.upperBoundIsStrict() ? "<" : "<=") + uTime;
throw new PrismException("Invalid upper bound " + bound + " in time-bounded until formula");
}
// model check operands first
b1 = checkExpression(model, expr.getOperand1()).getBitSet();
b2 = checkExpression(model, expr.getOperand2()).getBitSet();
// compute probabilities
// a trivial case: "U<=0"
if (uTime == 0) {
// prob is 1 in b2 states, 0 otherwise
probs = StateValues.createFromBitSetAsDoubles(b2, model);
} else {
res = computeBoundedUntilProbs((CTMDP) model, b1, b2, uTime, min);
probs = StateValues.createFromDoubleArray(res.soln, model);
}
return probs;
}
/** Compute probabilities for a bounded until operator. */
protected StateValues checkProbBoundedUntil(
Model model, ExpressionTemporal expr, boolean min1, boolean min2) throws PrismException {
int time;
BitSet b1, b2;
StateValues probs = null;
ModelCheckerResult res = null;
// get info from bounded until
time = expr.getUpperBound().evaluateInt(constantValues);
if (expr.upperBoundIsStrict()) time--;
if (time < 0) {
String bound = expr.upperBoundIsStrict() ? "<" + (time + 1) : "<=" + time;
throw new PrismException("Invalid bound " + bound + " in bounded until formula");
}
// model check operands first
b1 = checkExpression(model, expr.getOperand1()).getBitSet();
b2 = checkExpression(model, expr.getOperand2()).getBitSet();
// print out some info about num states
// mainLog.print("\nb1 = " + JDD.GetNumMintermsString(b1,
// allDDRowVars.n()));
// mainLog.print(" states, b2 = " + JDD.GetNumMintermsString(b2,
// allDDRowVars.n()) + " states\n");
// Compute probabilities
// a trivial case: "U<=0"
if (time == 0) {
// prob is 1 in b2 states, 0 otherwise
probs = StateValues.createFromBitSetAsDoubles(b2, model);
} else {
res = computeBoundedUntilProbs((STPG) model, b1, b2, time, min1, min2);
probs = StateValues.createFromDoubleArray(res.soln, model);
}
return probs;
}
/** Model check a P operator. */
private Result checkExpressionProb(ExpressionProb expr) throws PrismException {
boolean min;
ExpressionTemporal exprTemp;
Expression exprTarget;
BitSet targetLocs;
int timeBound;
boolean timeBoundStrict;
double prob;
// Check whether Pmin=? or Pmax=? (only two cases allowed)
if (expr.getProb() != null) {
throw new PrismException(
"PTA model checking currently only supports Pmin=? and Pmax=? properties (try the digital clocks engine instead)");
}
min = expr.getRelOp().equals("min=");
// Check this is a F path property (only case allowed at the moment)
if (!(expr.getExpression() instanceof ExpressionTemporal))
throw new PrismException(
"PTA model checking currently only supports the F path operator (try the digital clocks engine instead)");
exprTemp = (ExpressionTemporal) expr.getExpression();
if (exprTemp.getOperator() != ExpressionTemporal.P_F || !exprTemp.isSimplePathFormula())
throw new PrismException(
"PTA model checking currently only supports the F path operator (try the digital clocks engine instead)");
// Determine locations satisfying target
exprTarget = exprTemp.getOperand2();
targetLocs = checkLocationExpression(exprTarget);
mainLog.println(
"Target (" + exprTarget + ") satisfied by " + targetLocs.cardinality() + " locations.");
// mainLog.println(targetLocs);
// If there is a time bound, add a clock and encode this into target
if (exprTemp.hasBounds()) {
mainLog.println("Modifying PTA to encode time bound from property...");
// Get time bound info (is always of form <=T or <T)
timeBound = exprTemp.getUpperBound().evaluateInt(constantValues);
timeBoundStrict = exprTemp.upperBoundIsStrict();
// Modify PTA to include time bound; get new target
targetLocs = buildTimeBoundIntoPta(pta, targetLocs, timeBound, timeBoundStrict);
mainLog.println("New PTA: " + pta.infoString());
}
// Compute probability of reaching the set of target locations
prob = computeProbabilisticReachability(targetLocs, min);
// Return result
return new Result(new Double(prob));
}
