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Refactor explicit engine model checking of reward and steady state operators, as done recently for probabilistic stuff. 

git-svn-id: https://www.prismmodelchecker.org/svn/prism/prism/trunk@8686 bbc10eb1-c90d-0410-af57-cb519fbb1720
master
Dave Parker 12 years ago
parent
f67aee8fca
commit
22e7009d7b
4 changed files with 199 additions and 280 deletions
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  1. 33
      prism/src/explicit/CTMCModelChecker.java
  2. 115
      prism/src/explicit/DTMCModelChecker.java
  3. 92
      prism/src/explicit/MDPModelChecker.java
  4. 217
      prism/src/explicit/ProbModelChecker.java

33
prism/src/explicit/CTMCModelChecker.java
View File

@ -210,13 +210,13 @@ public class CTMCModelChecker extends DTMCModelChecker
/**
* Compute next=state probabilities.
* i.e. compute the probability of being in a state in {@code target} in the next step.
* @param dtmc The DTMC
* @param ctmc The CTMC
* @param target Target states
*/
public ModelCheckerResult computeNextProbs(DTMC dtmc, BitSet target) throws PrismException
public ModelCheckerResult computeNextProbs(CTMC ctmc, BitSet target) throws PrismException
{
mainLog.println("Building embedded DTMC...");
DTMC dtmcEmb = ((CTMC) dtmc).buildImplicitEmbeddedDTMC();
DTMC dtmcEmb = ctmc.buildImplicitEmbeddedDTMC();
return super.computeNextProbs(dtmcEmb, target);
}
@ -224,17 +224,17 @@ public class CTMCModelChecker extends DTMCModelChecker
* Compute reachability/until probabilities.
* i.e. compute the probability of reaching a state in {@code target},
* while remaining in those in @{code remain}.
* @param dtmc The CTMC
* @param ctmc The CTMC
* @param remain Remain in these states (optional: null means "all")
* @param target Target states
* @param init Optionally, an initial solution vector (may be overwritten)
* @param known Optionally, a set of states for which the exact answer is known
* Note: if 'known' is specified (i.e. is non-null, 'init' must also be given and is used for the exact values.
*/
public ModelCheckerResult computeReachProbs(DTMC dtmc, BitSet remain, BitSet target, double init[], BitSet known) throws PrismException
public ModelCheckerResult computeReachProbs(CTMC ctmc, BitSet remain, BitSet target, double init[], BitSet known) throws PrismException
{
mainLog.println("Building embedded DTMC...");
DTMC dtmcEmb = ((CTMC) dtmc).buildImplicitEmbeddedDTMC();
DTMC dtmcEmb = ctmc.buildImplicitEmbeddedDTMC();
return super.computeReachProbs(dtmcEmb, remain, target, init, known);
}
@ -398,8 +398,7 @@ public class CTMCModelChecker extends DTMCModelChecker
* @param mcRewards The rewards
* @param t Time bound
*/
@Override
public ModelCheckerResult computeCumulativeRewards(DTMC dtmc, MCRewards mcRewards, double t) throws PrismException
public ModelCheckerResult computeCumulativeRewards(CTMC ctmc, MCRewards mcRewards, double t) throws PrismException
{
ModelCheckerResult res = null;
int i, n, iters;
@ -413,7 +412,7 @@ public class CTMCModelChecker extends DTMCModelChecker
// Optimisation: If t = 0, this is easy.
if (t == 0) {
res = new ModelCheckerResult();
res.soln = new double[dtmc.getNumStates()];
res.soln = new double[ctmc.getNumStates()];
return res;
}
@ -421,8 +420,6 @@ public class CTMCModelChecker extends DTMCModelChecker
timer = System.currentTimeMillis();
mainLog.println("\nStarting backwards cumulative rewards computation...");
CTMC ctmc = (CTMC) dtmc;
// Store num states
n = ctmc.getNumStates();
@ -455,7 +452,7 @@ public class CTMCModelChecker extends DTMCModelChecker
mainLog.println("Fox-Glynn (" + acc + "): left = " + left + ", right = " + right);
// Build (implicit) uniformised DTMC
dtmc = ctmc.buildImplicitUniformisedDTMC(q);
DTMC dtmcUnif = ctmc.buildImplicitUniformisedDTMC(q);
// Create solution vector(s)
soln = new double[n];
@ -479,7 +476,7 @@ public class CTMCModelChecker extends DTMCModelChecker
iters = 1;
while (iters <= right) {
// Matrix-vector multiply
dtmc.mvMult(soln, soln2, null, false);
dtmcUnif.mvMult(soln, soln2, null, false);
// Swap vectors for next iter
tmpsoln = soln;
soln = soln2;
@ -618,21 +615,21 @@ public class CTMCModelChecker extends DTMCModelChecker
/**
* Compute expected reachability rewards.
* @param dtmc The CTMC
* @param ctmc The CTMC
* @param mcRewards The rewards
* @param target Target states
*/
public ModelCheckerResult computeReachRewards(DTMC dtmc, MCRewards mcRewards, BitSet target) throws PrismException
public ModelCheckerResult computeReachRewards(CTMC ctmc, MCRewards mcRewards, BitSet target) throws PrismException
{
int i, n;
// Build embedded DTMC
mainLog.println("Building embedded DTMC...");
DTMC dtmcEmb = ((CTMC) dtmc).buildImplicitEmbeddedDTMC();
DTMC dtmcEmb = ctmc.buildImplicitEmbeddedDTMC();
// Convert rewards
n = dtmc.getNumStates();
n = ctmc.getNumStates();
StateRewardsArray rewEmb = new StateRewardsArray(n);
for (i = 0; i < n; i++) {
rewEmb.setStateReward(i, mcRewards.getStateReward(i) / ((CTMC) dtmc).getExitRate(i));
rewEmb.setStateReward(i, mcRewards.getStateReward(i) / ctmc.getExitRate(i));
}
// Do computation on DTMC
return super.computeReachRewards(dtmcEmb, rewEmb, target);

115
prism/src/explicit/DTMCModelChecker.java
View File

@ -33,7 +33,6 @@ import java.util.Map;
import java.util.Vector;
import parser.ast.Expression;
import parser.ast.ExpressionTemporal;
import parser.type.TypeDouble;
import prism.DRA;
import prism.Pair;
@ -95,7 +94,6 @@ public class DTMCModelChecker extends ProbModelChecker
Pair<Model, int[]> pair = mcLtl.constructProductMC(dra, (DTMC) model, labelBS);
modelProduct = pair.first;
int invMap[] = pair.second;
int modelProductSize = modelProduct.getNumStates();
mainLog.print("\n" + modelProduct.infoStringTable());
// Find accepting BSCCs + compute reachability probabilities
@ -123,100 +121,6 @@ public class DTMCModelChecker extends ProbModelChecker
return probs;
}
/**
* Compute rewards for the contents of an R operator.
*/
protected StateValues checkRewardFormula(Model model, MCRewards modelRewards, Expression expr) throws PrismException
{
StateValues rewards = null;
if (expr instanceof ExpressionTemporal) {
ExpressionTemporal exprTemp = (ExpressionTemporal) expr;
switch (exprTemp.getOperator()) {
case ExpressionTemporal.R_F:
rewards = checkRewardReach(model, modelRewards, exprTemp);
break;
case ExpressionTemporal.R_I:
rewards = checkRewardInstantaneous(model, modelRewards, exprTemp);
break;
case ExpressionTemporal.R_C:
rewards = checkRewardCumulative(model, modelRewards, exprTemp);
break;
default:
throw new PrismException("Explicit engine does not yet handle the " + exprTemp.getOperatorSymbol() + " operator in the R operator");
}
}
if (rewards == null)
throw new PrismException("Unrecognised operator in R operator");
return rewards;
}
/**
* Compute rewards for a reachability reward operator.
*/
protected StateValues checkRewardReach(Model model, MCRewards modelRewards, ExpressionTemporal expr) throws PrismException
{
BitSet b;
StateValues rewards = null;
ModelCheckerResult res = null;
// model check operand first
b = checkExpression(model, expr.getOperand2()).getBitSet();
// print out some info about num states
// mainLog.print("\nb = " + JDD.GetNumMintermsString(b1,
// allDDRowVars.n()));
res = computeReachRewards((DTMC) model, modelRewards, b);
rewards = StateValues.createFromDoubleArray(res.soln, model);
return rewards;
}
/**
* Compute rewards for an instantaneous reward operator.
*/
protected StateValues checkRewardInstantaneous(Model model, MCRewards modelRewards, ExpressionTemporal expr) throws PrismException
{
StateValues rewards = null;
ModelCheckerResult res = null;
// get time bound
double t = expr.getUpperBound().evaluateDouble(constantValues);
// print out some info about num states
// mainLog.print("\nb = " + JDD.GetNumMintermsString(b1,
// allDDRowVars.n()));
res = computeInstantaneousRewards((DTMC) model, modelRewards, t);
rewards = StateValues.createFromDoubleArray(res.soln, model);
return rewards;
}
/**
* Compute rewards for a cumulative reward operator.
*/
protected StateValues checkRewardCumulative(Model model, MCRewards modelRewards, ExpressionTemporal expr) throws PrismException
{
StateValues rewards = null;
ModelCheckerResult res = null;
// get time bound
double t = expr.getUpperBound().evaluateDouble(constantValues);
// print out some info about num states
// mainLog.print("\nb = " + JDD.GetNumMintermsString(b1,
// allDDRowVars.n()));
res = computeCumulativeRewards((DTMC) model, modelRewards, t);
rewards = StateValues.createFromDoubleArray(res.soln, model);
return rewards;
}
public ModelCheckerResult computeInstantaneousRewards(DTMC dtmc, MCRewards mcRewards, double t) throws PrismException
{
ModelCheckerResult res = null;
@ -312,25 +216,6 @@ public class DTMCModelChecker extends ProbModelChecker
return res;
}
/**
* Compute steady-state probabilities for an S operator.
*/
protected StateValues checkSteadyStateFormula(Model model, Expression expr) throws PrismException
{
BitSet b;
StateValues probs = null;
ModelCheckerResult res = null;
// Model check operand first
b = checkExpression(model, expr).getBitSet();
double multProbs[] = Utils.bitsetToDoubleArray(b, model.getNumStates());
res = computeSteadyStateBackwardsProbs((DTMC) model, multProbs);
probs = StateValues.createFromDoubleArray(res.soln, model);
return probs;
}
// Steady-state/transient probability computation
/**

92
prism/src/explicit/MDPModelChecker.java
View File

@ -33,8 +33,6 @@ import java.util.Map;
import java.util.Vector;
import parser.ast.Expression;
import parser.ast.ExpressionTemporal;
import parser.type.TypeDouble;
import prism.DRA;
import prism.Pair;
import prism.PrismComponent;
@ -106,7 +104,6 @@ public class MDPModelChecker extends ProbModelChecker
Pair<NondetModel, int[]> pair = mcLtl.constructProductMDP(dra, (MDP) model, labelBS);
modelProduct = pair.first;
int invMap[] = pair.second;
int modelProductSize = modelProduct.getNumStates();
// Find accepting MECs + compute reachability probabilities
mainLog.println("\nFinding accepting MECs...");
@ -139,93 +136,6 @@ public class MDPModelChecker extends ProbModelChecker
return probs;
}
/**
* Compute rewards for the contents of an R operator.
*/
protected StateValues checkRewardFormula(NondetModel model, MDPRewards modelRewards, Expression expr, boolean min) throws PrismException
{
StateValues rewards = null;
if (expr instanceof ExpressionTemporal) {
ExpressionTemporal exprTemp = (ExpressionTemporal) expr;
switch (exprTemp.getOperator()) {
case ExpressionTemporal.R_C:
rewards = checkRewardCumul(model, modelRewards, exprTemp, min);
break;
case ExpressionTemporal.R_F:
rewards = checkRewardReach(model, modelRewards, exprTemp, min);
break;
default:
throw new PrismException("Explicit engine does not yet handle the " + exprTemp.getOperatorSymbol() + " operator in the R operator");
}
}
if (rewards == null)
throw new PrismException("Unrecognised operator in R operator");
return rewards;
}
/**
* Compute rewards for a cumulative reward operator.
*/
protected StateValues checkRewardCumul(NondetModel model, MDPRewards modelRewards, ExpressionTemporal expr, boolean min) throws PrismException
{
int time; // time
StateValues rewards = null;
ModelCheckerResult res = null;
// check that there is an upper time bound
if (expr.getUpperBound() == null) {
throw new PrismException("Cumulative reward operator without time bound (C) is only allowed for multi-objective queries");
}
// get info from inst reward
time = expr.getUpperBound().evaluateInt(constantValues);
if (time < 0) {
throw new PrismException("Invalid time bound " + time + " in cumulative reward formula");
}
// a trivial case: "<=0"
if (time == 0) {
rewards = new StateValues(TypeDouble.getInstance(), model.getNumStates(), new Double(0));
} else {
// compute rewards
try {
res = computeCumulRewards((MDP) model, modelRewards, time, min);
rewards = StateValues.createFromDoubleArray(res.soln, model);
result.setStrategy(res.strat);
} catch (PrismException e) {
throw e;
}
}
return rewards;
}
/**
* Compute rewards for a reachability reward operator.
*/
protected StateValues checkRewardReach(NondetModel model, MDPRewards modelRewards, ExpressionTemporal expr, boolean min) throws PrismException
{
BitSet b;
StateValues rewards = null;
ModelCheckerResult res = null;
// model check operand first
b = checkExpression(model, expr.getOperand2()).getBitSet();
// print out some info about num states
// mainLog.print("\nb = " + JDD.GetNumMintermsString(b1,
// allDDRowVars.n()));
res = computeReachRewards((MDP) model, modelRewards, b, min);
rewards = StateValues.createFromDoubleArray(res.soln, model);
result.setStrategy(res.strat);
return rewards;
}
// Numerical computation functions
/**
@ -1148,7 +1058,7 @@ public class MDPModelChecker extends ProbModelChecker
* @param target Target states
* @param min Min or max rewards (true=min, false=max)
*/
public ModelCheckerResult computeCumulRewards(MDP mdp, MDPRewards mdpRewards, int k, boolean min) throws PrismException
public ModelCheckerResult computeCumulativeRewards(MDP mdp, MDPRewards mdpRewards, int k, boolean min) throws PrismException
{
ModelCheckerResult res = null;
int i, n, iters;

217
prism/src/explicit/ProbModelChecker.java
View File

@ -36,13 +36,14 @@ import parser.ast.ExpressionTemporal;
import parser.ast.ExpressionUnaryOp;
import parser.ast.RelOp;
import parser.ast.RewardStruct;
import prism.ModelType;
import parser.type.TypeDouble;
import prism.PrismComponent;
import prism.PrismException;
import prism.PrismSettings;
import explicit.rewards.ConstructRewards;
import explicit.rewards.MCRewards;
import explicit.rewards.MDPRewards;
import explicit.rewards.Rewards;
/**
* Super class for explicit-state probabilistic model checkers.
@ -468,10 +469,9 @@ public class ProbModelChecker extends NonProbModelChecker
Expression pb; // Probability bound (expression)
double p = 0; // Probability bound (actual value)
RelOp relOp; // Relational operator
StateValues probs = null;
// Get info from prob operator
// Get info from P operator
relOp = expr.getRelOp();
pb = expr.getProb();
if (pb != null) {
@ -612,7 +612,7 @@ public class ProbModelChecker extends NonProbModelChecker
throw new PrismException("Invalid bound " + bound + " in bounded until formula");
}
// Model check operands first
// Model check operands
BitSet remain = checkExpression(model, expr.getOperand1()).getBitSet();
BitSet target = checkExpression(model, expr.getOperand2()).getBitSet();
@ -644,7 +644,7 @@ public class ProbModelChecker extends NonProbModelChecker
*/
protected StateValues checkProbUntil(Model model, ExpressionTemporal expr, MinMax minMax) throws PrismException
{
// Model check operands first
// Model check operands
BitSet remain = checkExpression(model, expr.getOperand1()).getBitSet();
BitSet target = checkExpression(model, expr.getOperand2()).getBitSet();
@ -689,14 +689,11 @@ public class ProbModelChecker extends NonProbModelChecker
Expression rb; // Reward bound (expression)
double r = 0; // Reward bound (actual value)
RelOp relOp; // Relational operator
boolean min = false; // For nondeterministic models, are we finding min (true) or max (false) rewards
ModelType modelType = model.getModelType();
StateValues rews = null;
MCRewards mcRewards = null;
MDPRewards mdpRewards = null;
Rewards rewards = null;
int i;
// Get info from reward operator
// Get info from R operator
rs = expr.getRewardStructIndex();
relOp = expr.getRelOp();
rb = expr.getReward();
@ -705,7 +702,6 @@ public class ProbModelChecker extends NonProbModelChecker
if (r < 0)
throw new PrismException("Invalid reward bound " + r + " in R[] formula");
}
min = relOp.isLowerBound() || relOp.isMin();
// Get reward info
if (modulesFile == null)
@ -725,36 +721,25 @@ public class ProbModelChecker extends NonProbModelChecker
throw new PrismException("Invalid reward structure index \"" + rs + "\"");
// Build rewards
mainLog.println("Building reward structure...");
ConstructRewards constructRewards = new ConstructRewards(mainLog);
switch (modelType) {
switch (model.getModelType()) {
case CTMC:
case DTMC:
mcRewards = constructRewards.buildMCRewardStructure((DTMC) model, rewStruct, constantValues);
rewards = constructRewards.buildMCRewardStructure((DTMC) model, rewStruct, constantValues);
break;
case MDP:
mdpRewards = constructRewards.buildMDPRewardStructure((MDP) model, rewStruct, constantValues);
rewards = constructRewards.buildMDPRewardStructure((MDP) model, rewStruct, constantValues);
break;
default:
throw new PrismException("Cannot build rewards for " + modelType + "s");
throw new PrismException("Cannot build rewards for " + model.getModelType() + "s");
}
// Compute rewards
mainLog.println("Building reward structure...");
switch (modelType) {
case CTMC:
rews = ((CTMCModelChecker) this).checkRewardFormula(model, mcRewards, expr.getExpression());
break;
case DTMC:
rews = ((DTMCModelChecker) this).checkRewardFormula(model, mcRewards, expr.getExpression());
break;
case MDP:
rews = ((MDPModelChecker) this).checkRewardFormula((NondetModel) model, mdpRewards, expr.getExpression(), min);
break;
default:
throw new PrismException("Cannot model check " + expr + " for " + modelType + "s");
}
MinMax minMax = (relOp.isLowerBound() || relOp.isMin()) ? MinMax.min() : MinMax.max();
rews = checkRewardFormula(model, rewards, expr.getExpression(), minMax);
// Print out probabilities
// Print out rewards
if (getVerbosity() > 5) {
mainLog.print("\nRewards (non-zero only) for all states:\n");
rews.print(mainLog);
@ -772,6 +757,139 @@ public class ProbModelChecker extends NonProbModelChecker
}
}
/**
* Compute rewards for the contents of an R operator.
*/
protected StateValues checkRewardFormula(Model model, Rewards modelRewards, Expression expr, MinMax minMax) throws PrismException
{
StateValues rewards = null;
if (expr instanceof ExpressionTemporal) {
ExpressionTemporal exprTemp = (ExpressionTemporal) expr;
switch (exprTemp.getOperator()) {
case ExpressionTemporal.R_F:
rewards = checkRewardReach(model, modelRewards, exprTemp, minMax);
break;
case ExpressionTemporal.R_I:
rewards = checkRewardInstantaneous(model, modelRewards, exprTemp, minMax);
break;
case ExpressionTemporal.R_C:
rewards = checkRewardCumulative(model, modelRewards, exprTemp, minMax);
break;
default:
throw new PrismException("Explicit engine does not yet handle the " + exprTemp.getOperatorSymbol() + " reward operator");
}
}
if (rewards == null)
throw new PrismException("Unrecognised operator in R operator");
return rewards;
}
/**
* Compute rewards for a reachability reward operator.
*/
protected StateValues checkRewardReach(Model model, Rewards modelRewards, ExpressionTemporal expr, MinMax minMax) throws PrismException
{
// Model check the operand
BitSet target = checkExpression(model, expr.getOperand2()).getBitSet();
// Compute/return the rewards
ModelCheckerResult res = null;
switch (model.getModelType()) {
case DTMC:
res = ((DTMCModelChecker) this).computeReachRewards((DTMC) model, (MCRewards) modelRewards, target);
break;
case CTMC:
res = ((CTMCModelChecker) this).computeReachRewards((CTMC) model, (MCRewards) modelRewards, target);
break;
case MDP:
res = ((MDPModelChecker) this).computeReachRewards((MDP) model, (MDPRewards) modelRewards, target, minMax.isMin());
result.setStrategy(res.strat);
break;
default:
throw new PrismException("Explicit engine does not yet handle the " + expr.getOperatorSymbol() + " reward operator for " + model.getModelType()
+ "s");
}
return StateValues.createFromDoubleArray(res.soln, model);
}
/**
* Compute rewards for an instantaneous reward operator.
*/
protected StateValues checkRewardInstantaneous(Model model, Rewards modelRewards, ExpressionTemporal expr, MinMax minMax) throws PrismException
{
// Get time bound
double t = expr.getUpperBound().evaluateDouble(constantValues);
// Compute/return the rewards
ModelCheckerResult res = null;
switch (model.getModelType()) {
case DTMC:
res = ((DTMCModelChecker) this).computeInstantaneousRewards((DTMC) model, (MCRewards) modelRewards, t);
break;
case CTMC:
res = ((CTMCModelChecker) this).computeInstantaneousRewards((CTMC) model, (MCRewards) modelRewards, t);
break;
default:
throw new PrismException("Explicit engine does not yet handle the " + expr.getOperatorSymbol() + " reward operator for " + model.getModelType()
+ "s");
}
return StateValues.createFromDoubleArray(res.soln, model);
}
/**
* Compute rewards for a cumulative reward operator.
*/
protected StateValues checkRewardCumulative(Model model, Rewards modelRewards, ExpressionTemporal expr, MinMax minMax) throws PrismException
{
int timeInt = -1;
double timeDouble = -1;
// Check that there is an upper time bound
if (expr.getUpperBound() == null) {
throw new PrismException("Cumulative reward operator without time bound (C) is only allowed for multi-objective queries");
}
// Get time bound
if (model.getModelType().continuousTime()) {
timeDouble = expr.getUpperBound().evaluateDouble(constantValues);
if (timeDouble < 0) {
throw new PrismException("Invalid time bound " + timeDouble + " in cumulative reward formula");
}
} else {
timeInt = expr.getUpperBound().evaluateInt(constantValues);
if (timeInt < 0) {
throw new PrismException("Invalid time bound " + timeInt + " in cumulative reward formula");
}
}
// Compute/return the rewards
// A trivial case: "C<=0" (prob is 1 in target states, 0 otherwise)
if (timeInt == 0 || timeDouble == 0) {
return new StateValues(TypeDouble.getInstance(), model.getNumStates(), new Double(0));
}
// Otherwise: numerical solution
ModelCheckerResult res = null;
switch (model.getModelType()) {
case DTMC:
res = ((DTMCModelChecker) this).computeCumulativeRewards((DTMC) model, (MCRewards) modelRewards, timeInt);
break;
case CTMC:
res = ((CTMCModelChecker) this).computeCumulativeRewards((CTMC) model, (MCRewards) modelRewards, timeDouble);
break;
case MDP:
res = ((MDPModelChecker) this).computeCumulativeRewards((MDP) model, (MDPRewards) modelRewards, timeInt, minMax.isMin());
result.setStrategy(res.strat);
break;
default:
throw new PrismException("Explicit engine does not yet handle the " + expr.getOperatorSymbol() + " reward operator for " + model.getModelType()
+ "s");
}
return StateValues.createFromDoubleArray(res.soln, model);
}
/**
* Model check an S operator expression and return the values for all states.
*/
@ -780,11 +898,9 @@ public class ProbModelChecker extends NonProbModelChecker
Expression pb; // Probability bound (expression)
double p = 0; // Probability bound (actual value)
RelOp relOp; // Relational operator
ModelType modelType = model.getModelType();
StateValues probs = null;
// Get info from prob operator
// Get info from S operator
relOp = expr.getRelOp();
pb = expr.getProb();
if (pb != null) {
@ -793,19 +909,9 @@ public class ProbModelChecker extends NonProbModelChecker
throw new PrismException("Invalid probability bound " + p + " in P operator");
}
// Compute probabilities
switch (modelType) {
case CTMC:
//probs = ((CTMCModelChecker) this).checkSteadyStateFormula(model, expr.getExpression());
//break;
throw new PrismException("Explicit engine does not yet support the S operator for CTMCs");
case DTMC:
probs = ((DTMCModelChecker) this).checkSteadyStateFormula(model, expr.getExpression());
break;
default:
throw new PrismException("Cannot model check " + expr + " for a " + modelType);
}
MinMax minMax = (relOp.isLowerBound() || relOp.isMin()) ? MinMax.min() : MinMax.max();
probs = checkSteadyStateFormula(model, expr.getExpression(), minMax);
// Print out probabilities
if (getVerbosity() > 5) {
@ -824,4 +930,25 @@ public class ProbModelChecker extends NonProbModelChecker
return StateValues.createFromBitSet(sol, model);
}
}
/**
* Compute steady-state probabilities for an S operator.
*/
protected StateValues checkSteadyStateFormula(Model model, Expression expr, MinMax minMax) throws PrismException
{
// Model check operand
BitSet b = checkExpression(model, expr).getBitSet();
// Compute/return the probabilities
ModelCheckerResult res = null;
switch (model.getModelType()) {
case DTMC:
double multProbs[] = Utils.bitsetToDoubleArray(b, model.getNumStates());
res = ((DTMCModelChecker) this).computeSteadyStateBackwardsProbs((DTMC) model, multProbs);
break;
default:
throw new PrismException("Explicit engine does not yet handle the S operator for " + model.getModelType() + "s");
}
return StateValues.createFromDoubleArray(res.soln, model);
}
}
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