/// <summary>
/// [ REFS: '', DEREFS:]
/// </summary>
/// <param name="allProb"></param>
/// <param name="state"></param>
public double GetMinProb(CUDDNode allProb, CUDDNode filter)
{
double result = 0;
CUDD.Ref(filter, reach);
CUDDNode newFilter = CUDD.Function.And(filter, reach);
if (newFilter.Equals(CUDD.ZERO))
{
result = double.MaxValue;
}
else
{
CUDD.Ref(newFilter, allProb);
CUDDNode tmp = CUDD.Function.ITE(newFilter, allProb, CUDD.PlusInfinity());
result = CUDD.FindMin(tmp);
CUDD.Deref(tmp);
}
CUDD.Deref(newFilter);
return(result);
}
/// <summary>
/// Calculate state rewards and store in stateRewards
/// Transition rewards are prepared and stored in sysDDs
/// </summary>
/// <param name="sysDDs"></param>
private void ComputeRewards(SystemDDs sysDDs)
{
int numRewardStructs = modules.rewardStructs.Count;
//Initialize reward of State and the resulted SystemDDs sysDDs
for (int j = 0; j < numRewardStructs; j++)
{
stateRewards.Add(CUDD.Constant(0));
sysDDs.ind.rewards.Add(CUDD.Constant(0));
for (int i = 0; i < synchs.Count; i++)
{
sysDDs.synchs[i].rewards.Add(CUDD.Constant(0));
}
}
// for each reward structure...
for (int j = 0; j < numRewardStructs; j++)
{
// get reward struct
RewardStruct rs = modules.rewardStructs[j];
// work through list of items in reward struct
foreach (var rewardItem in rs.items)
{
// translate states predicate and reward expression
CUDDNode guard = EncodeExpression(rewardItem.guard);
CUDDNode rewards = EncodeExpression(rewardItem.reward);
CUDDNode rewardDD;
string synch = rewardItem.synch;
if (synch == null)
{
// first case: item corresponds to state rewards
// restrict rewards to relevant states
rewardDD = CUDD.Function.Times(guard, rewards);
// check for negative rewards
if (CUDD.FindMin(rewardDD) < 0)
{
throw new Exception("Reward structure item with guard " + rewardItem.guard + " contains negative rewards");
}
// add to state rewards
stateRewards[j] = CUDD.Function.Plus(stateRewards[j], rewardDD);
}
else
{
// second case: item corresponds to transition rewards
//find the corresponding component to update the reward
ComponentDDs compDDs;
// work out which (if any) action this is for
if (synch == string.Empty)
{
compDDs = sysDDs.ind;
}
else if (synchs.Contains(synch))
{
int k = synchs.IndexOf(synch);
compDDs = sysDDs.synchs[k];
}
else
{
throw new Exception("Invalid action name \"" + synch + "\" in reward structure item");
}
// identify corresponding transitions
// (for dtmcs/ctmcs, keep actual values - need to weight rewards; for mdps just store 0/1)
CUDD.Ref(compDDs.trans);
rewardDD = (modules.modelType == ModelType.MDP)? (CUDD.Convert.GreaterThan(compDDs.trans, 0)): compDDs.trans;
// restrict to relevant states
rewardDD = CUDD.Function.Times(rewardDD, guard);
// multiply by reward values
rewardDD = CUDD.Function.Times(rewardDD, rewards);
// check for negative rewards
if (CUDD.FindMin(rewardDD) < 0)
{
throw new Exception("Reward structure item with guard " + rewardItem.guard + " contains negative rewards");
}
// add result to rewards
compDDs.rewards[j] = CUDD.Function.Plus(compDDs.rewards[j], rewardDD);
}
}
}
}
