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)); }