From 527713964085ae21879994fc5235106ebd9126c0 Mon Sep 17 00:00:00 2001
From: Sebastian Junges <sebastian.junges@gmail.com>
Date: Thu, 23 Apr 2020 15:49:43 -0700
Subject: [PATCH] first version of a generator for belief support MDPs

---
 .../generator/BeliefSupportTracker.cpp        | 35 +++++++++++++++++++
 .../generator/BeliefSupportTracker.h          | 26 ++++++++++++++
 2 files changed, 61 insertions(+)
 create mode 100644 src/storm-pomdp/generator/BeliefSupportTracker.cpp
 create mode 100644 src/storm-pomdp/generator/BeliefSupportTracker.h

diff --git a/src/storm-pomdp/generator/BeliefSupportTracker.cpp b/src/storm-pomdp/generator/BeliefSupportTracker.cpp
new file mode 100644
index 000000000..be2138121
--- /dev/null
+++ b/src/storm-pomdp/generator/BeliefSupportTracker.cpp
@@ -0,0 +1,35 @@
+#include "storm-pomdp/generator/BeliefSupportTracker.h"
+
+namespace storm {
+    namespace generator {
+        template<typename ValueType>
+        BeliefSupportTracker<ValueType>::BeliefSupportTracker(storm::models::sparse::Pomdp<ValueType> const& pomdp) :
+        pomdp(pomdp), currentBeliefSupport(pomdp.getInitialStates())
+        {
+
+        }
+
+        template<typename ValueType>
+        storm::storage::BitVector const& BeliefSupportTracker<ValueType>::getCurrentBeliefSupport() const {
+            return currentBeliefSupport;
+        }
+
+        template<typename ValueType>
+        void BeliefSupportTracker<ValueType>::track(uint64_t action, uint64_t observation) {
+            storm::storage::BitVector newBeliefSupport(pomdp.getNumberOfStates());
+            for (uint64_t oldState : currentBeliefSupport) {
+                uint64_t row = pomdp.getTransitionMatrix().getRowGroupIndices()[oldState] + action;
+                for (auto const& successor : pomdp.getTransitionMatrix().getRow(row)) {
+                    assert(!storm::utility::isZero(successor.getValue()));
+                    if (pomdp.getObservation(successor.getColumn()) == observation) {
+                        newBeliefSupport.set(successor.getColumn(), true);
+                    }
+                }
+            }
+            currentBeliefSupport = newBeliefSupport;
+        }
+
+        template class BeliefSupportTracker<double>;
+
+    }
+}
\ No newline at end of file
diff --git a/src/storm-pomdp/generator/BeliefSupportTracker.h b/src/storm-pomdp/generator/BeliefSupportTracker.h
new file mode 100644
index 000000000..dcd133043
--- /dev/null
+++ b/src/storm-pomdp/generator/BeliefSupportTracker.h
@@ -0,0 +1,26 @@
+#include "storm/models/sparse/Pomdp.h"
+#include "storm/storage/BitVector.h"
+
+namespace storm {
+    namespace generator {
+        template<typename ValueType>
+        class BeliefSupportTracker {
+            /**
+             * Tracks the current belief support.
+             * TODO refactor into tracker and generator.
+             * @param pomdp
+             */
+        public:
+            BeliefSupportTracker(storm::models::sparse::Pomdp<ValueType> const& pomdp);
+
+            storm::storage::BitVector const& getCurrentBeliefSupport() const;
+
+            void track(uint64_t action, uint64_t observation);
+
+        private:
+            storm::models::sparse::Pomdp<ValueType> const& pomdp;
+            storm::storage::BitVector currentBeliefSupport;
+
+        };
+    }
+}
\ No newline at end of file