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Two bugs in LTL model checking for MDPs. 

git-svn-id: https://www.prismmodelchecker.org/svn/prism/prism/trunk@2201 bbc10eb1-c90d-0410-af57-cb519fbb1720
master
Dave Parker 15 years ago
parent
b6d4a15737
commit
31707a7729
1 changed files with 42 additions and 51 deletions
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  1. 81
      prism/src/prism/LTLModelChecker.java

81
prism/src/prism/LTLModelChecker.java
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@ -57,8 +57,7 @@ public class LTLModelChecker
* actual true/false, and duplicate results are given the same label. BDDs giving the states which satisfy each label
* are put into the vector labelDDs, which should be empty when this function is called.
*/
public Expression checkMaximalStateFormulas(ModelChecker mc, Model model, Expression expr, Vector<JDDNode> labelDDs)
throws PrismException
public Expression checkMaximalStateFormulas(ModelChecker mc, Model model, Expression expr, Vector<JDDNode> labelDDs) throws PrismException
{
// A state formula
if (expr.getType() instanceof TypeBool) {
@ -125,8 +124,8 @@ public class LTLModelChecker
* @param draDDRowVarsCopy: (Optionally) empty JDDVars object to obtain copy of DD row vars for DRA
* @param draDDColVarsCopy: (Optionally) empty JDDVars object to obtain copy of DD col vars for DRA
*/
public ProbModel constructProductMC(DRA dra, ProbModel model, Vector<JDDNode> labelDDs, JDDVars draDDRowVarsCopy,
JDDVars draDDColVarsCopy) throws PrismException
public ProbModel constructProductMC(DRA dra, ProbModel model, Vector<JDDNode> labelDDs, JDDVars draDDRowVarsCopy, JDDVars draDDColVarsCopy)
throws PrismException
{
return constructProductMC(dra, model, labelDDs, draDDRowVarsCopy, draDDColVarsCopy, true);
}
@ -140,8 +139,8 @@ public class LTLModelChecker
* @param draDDColVarsCopy: (Optionally) empty JDDVars object to obtain copy of DD col vars for DRA
* @param allInit: Do we assume that all states of the original model are initial states? (see below)
*/
public ProbModel constructProductMC(DRA dra, ProbModel model, Vector<JDDNode> labelDDs, JDDVars draDDRowVarsCopy,
JDDVars draDDColVarsCopy, boolean allInit) throws PrismException
public ProbModel constructProductMC(DRA dra, ProbModel model, Vector<JDDNode> labelDDs, JDDVars draDDRowVarsCopy, JDDVars draDDColVarsCopy, boolean allInit)
throws PrismException
{
// Existing model - dds, vars, etc.
JDDVars varDDRowVars[];
@ -232,8 +231,7 @@ public class LTLModelChecker
}
newVarList = (VarList) varList.clone();
// NB: if DRA only has one state, we add an extra dummy state
Declaration decl = new Declaration(draVar, new DeclarationInt(Expression.Int(0), Expression.Int(Math.max(dra
.size() - 1, 1))));
Declaration decl = new Declaration(draVar, new DeclarationInt(Expression.Int(0), Expression.Int(Math.max(dra.size() - 1, 1))));
newVarList.addVar(before ? 0 : varList.getNumVars(), decl, 1, model.getConstantValues());
// Extra references (because will get derefed when new model is done with)
@ -317,8 +315,8 @@ public class LTLModelChecker
* @param draDDRowVarsCopy: (Optionally) empty JDDVars object to obtain copy of DD row vars for DRA
* @param draDDColVarsCopy: (Optionally) empty JDDVars object to obtain copy of DD col vars for DRA
*/
public NondetModel constructProductMDP(DRA dra, NondetModel model, Vector<JDDNode> labelDDs, JDDVars draDDRowVarsCopy,
JDDVars draDDColVarsCopy) throws PrismException
public NondetModel constructProductMDP(DRA dra, NondetModel model, Vector<JDDNode> labelDDs, JDDVars draDDRowVarsCopy, JDDVars draDDColVarsCopy)
throws PrismException
{
return constructProductMDP(dra, model, labelDDs, draDDRowVarsCopy, draDDColVarsCopy, true);
}
@ -332,8 +330,8 @@ public class LTLModelChecker
* @param draDDColVarsCopy: (Optionally) empty JDDVars object to obtain copy of DD col vars for DRA
* @param allInit: Do we assume that all states of the original model are initial states? (see below)
*/
public NondetModel constructProductMDP(DRA dra, NondetModel model, Vector<JDDNode> labelDDs, JDDVars draDDRowVarsCopy,
JDDVars draDDColVarsCopy, boolean allInit) throws PrismException
public NondetModel constructProductMDP(DRA dra, NondetModel model, Vector<JDDNode> labelDDs, JDDVars draDDRowVarsCopy, JDDVars draDDColVarsCopy,
boolean allInit) throws PrismException
{
// Existing model - dds, vars, etc.
JDDVars varDDRowVars[];
@ -424,8 +422,7 @@ public class LTLModelChecker
}
newVarList = (VarList) varList.clone();
// NB: if DRA only has one state, we add an extra dummy state
Declaration decl = new Declaration(draVar, new DeclarationInt(Expression.Int(0), Expression.Int(Math.max(dra
.size() - 1, 1))));
Declaration decl = new Declaration(draVar, new DeclarationInt(Expression.Int(0), Expression.Int(Math.max(dra.size() - 1, 1))));
newVarList.addVar(before ? 0 : varList.getNumVars(), decl, 1, model.getConstantValues());
// Extra references (because will get derefed when new model is done with)
@ -469,8 +466,7 @@ public class LTLModelChecker
// New list of all row/col vars
newAllDDRowVars, newAllDDColVars,
// Nondet variables (unchanged)
model.getAllDDSchedVars(), model.getAllDDSynchVars(), model.getAllDDChoiceVars(), model
.getAllDDNondetVars(),
model.getAllDDSchedVars(), model.getAllDDSynchVars(), model.getAllDDChoiceVars(), model.getAllDDNondetVars(),
// New list of var names
newDDVarNames,
// Module info (unchanged)
@ -516,8 +512,7 @@ public class LTLModelChecker
*
* @return a referenced mask BDD over trans
*/
public JDDNode buildTransMask(DRA dra, Vector<JDDNode> labelDDs, JDDVars allDDRowVars, JDDVars allDDColVars,
JDDVars draDDRowVars, JDDVars draDDColVars)
public JDDNode buildTransMask(DRA dra, Vector<JDDNode> labelDDs, JDDVars allDDRowVars, JDDVars allDDColVars, JDDVars draDDRowVars, JDDVars draDDColVars)
{
Iterator<DA_State> it;
DA_State state;
@ -546,8 +541,7 @@ public class LTLModelChecker
// Switch label BDD to col vars
label = JDD.PermuteVariables(label, allDDRowVars, allDDColVars);
// Build a BDD for the edge
transition = JDD.SetMatrixElement(JDD.Constant(0), draDDRowVars, draDDColVars, state.getName(), edge
.getValue().getName(), 1);
transition = JDD.SetMatrixElement(JDD.Constant(0), draDDRowVars, draDDColVars, state.getName(), edge.getValue().getName(), 1);
// Now get the conjunction of the two
transition = JDD.And(transition, label);
// Add edge BDD to the DRA transition mask
@ -601,8 +595,7 @@ public class LTLModelChecker
*
* @returns a referenced BDD of the union of all the accepting sets
*/
public JDDNode findAcceptingBSCCs(DRA dra, JDDVars draDDRowVars, JDDVars draDDColVars, ProbModel model)
throws PrismException
public JDDNode findAcceptingBSCCs(DRA dra, JDDVars draDDRowVars, JDDVars draDDColVars, ProbModel model) throws PrismException
{
SCCComputer sccComputer;
JDDNode acceptingStates, allAcceptingStates;
@ -681,8 +674,7 @@ public class LTLModelChecker
*
* @returns a referenced BDD of the union of all the accepting sets
*/
public JDDNode findAcceptingStates(DRA dra, NondetModel model, JDDVars draDDRowVars, JDDVars draDDColVars,
boolean fairness) throws PrismException
public JDDNode findAcceptingStates(DRA dra, NondetModel model, JDDVars draDDRowVars, JDDVars draDDColVars, boolean fairness) throws PrismException
{
JDDNode acceptingStates, allAcceptingStates;
int i, j;
@ -825,10 +817,8 @@ public class LTLModelChecker
* BDD of a set of states (dereferenced after calling this function)
* @return a vector of referenced BDDs containing all the ECs in states
*/
private Vector<JDDNode> findEndComponents(NondetModel model, JDDNode states) throws PrismException
public Vector<JDDNode> findEndComponents(NondetModel model, JDDNode states) throws PrismException
{
boolean initialCandidate = true;
Stack<JDDNode> candidates = new Stack<JDDNode>();
candidates.push(states);
Vector<JDDNode> ecs = new Vector<JDDNode>();
@ -836,11 +826,9 @@ public class LTLModelChecker
while (!candidates.isEmpty()) {
JDDNode candidate = candidates.pop();
// Compute the stable set
JDD.Ref(candidate);
JDDNode stableSet = findMaximalStableSet(model, candidate);
// Drop empty sets
if (stableSet.equals(JDD.ZERO)) {
JDD.Deref(stableSet);
@ -848,17 +836,11 @@ public class LTLModelChecker
continue;
}
if (!initialCandidate) {
// candidate is an SCC, check if it's stable
if (stableSet.equals(candidate)) {
ecs.add(candidate);
JDD.Deref(stableSet);
continue;
}
} else {
initialCandidate = false;
if (stableSet.equals(candidate) && JDD.GetNumMinterms(stableSet, model.getNumDDRowVars()) == 1) {
ecs.add(candidate);
JDD.Deref(stableSet);
continue;
}
JDD.Deref(candidate);
// Filter bad transitions
JDD.Ref(stableSet);
@ -866,15 +848,22 @@ public class LTLModelChecker
// now find the maximal SCCs in (stableSet, stableSetTrans)
Vector<JDDNode> sccs;
sccComputer = prism.getSCCComputer(stableSet, stableSetTrans, model.getAllDDRowVars(), model
.getAllDDColVars());
sccComputer = prism.getSCCComputer(stableSet, stableSetTrans, model.getAllDDRowVars(), model.getAllDDColVars());
sccComputer.computeSCCs();
JDD.Deref(stableSet);
JDD.Deref(stableSetTrans);
sccs = sccComputer.getVectSCCs();
mainLog.println("SCC computer found " + sccs.size() + " SCCs");
JDD.Deref(sccComputer.getNotInSCCs());
candidates.addAll(sccs);
if (sccs.size() > 0) {
if (sccs.size() > 1 || !sccs.get(0).equals(candidate)) {
candidates.addAll(sccs);
JDD.Deref(candidate);
} else {
ecs.add(candidate);
JDD.Deref(sccs.get(0));
}
} else
JDD.Deref(candidate);
}
return ecs;
}
@ -959,8 +948,10 @@ public class LTLModelChecker
{
JDDNode union = JDD.Constant(0);
for (JDDNode set : sets) {
JDD.Ref(filter);
union = JDD.Or(union, JDD.And(set, filter));
if (JDD.AreInterecting(set, filter))
union = JDD.Or(union, set);
else
JDD.Deref(set);
}
JDD.Deref(filter);
return union;

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