From 55eeeb6bac3ea870f75fe8fab72fdb86a38ad756 Mon Sep 17 00:00:00 2001
From: Roman Andriushchenko <iandri@fit.vut.cz>
Date: Fri, 6 Dec 2024 16:16:06 +0100
Subject: [PATCH] handle POMDPs with unreachable observations

---
 paynt/quotient/fsc.py   | 13 ++++++++-----
 paynt/quotient/pomdp.py |  3 +++
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/paynt/quotient/fsc.py b/paynt/quotient/fsc.py
index b9e88e04..3452ebce 100644
--- a/paynt/quotient/fsc.py
+++ b/paynt/quotient/fsc.py
@@ -66,12 +66,15 @@ def check_action_function(self, observation_to_actions):
             assert len(self.action_function[node]) == self.num_observations, \
                 "in memory node {}, FSC action function is not defined for all observations".format(node)
             for obs in range(self.num_observations):
+                if observation_to_actions[obs] == []:
+                    assert self.action_function[node][obs] is None
+                    continue
                 if self.is_deterministic:
-                    action = self.action_function[node][obs]
-                    assert action in observation_to_actions[obs], "in observation {} FSC chooses invalid action {}".format(obs,action)
+                    action_support = [self.action_function[node][obs]]
                 else:
-                    for action,_ in self.action_function[node][obs].items():
-                        assert action in observation_to_actions[obs], "in observation {} FSC chooses invalid action {}".format(obs,action)
+                    action_support = self.action_function[node][obs].keys()
+                for action in action_support:
+                    assert action in observation_to_actions[obs], "in observation {} FSC chooses invalid action {}".format(obs,action)
 
     def check_update_function(self):
         assert len(self.update_function) == self.num_nodes, "FSC update function is not defined for all memory nodes"
@@ -91,7 +94,7 @@ def check(self, observation_to_actions):
     def fill_trivial_actions(self, observation_to_actions):
         ''' For each observation with 1 available action, set gamma(n,z) to that action. '''
         for obs,actions in enumerate(observation_to_actions):
-            if len(actions)>1:
+            if len(actions) != 1:
                 continue
             action = actions[0]
             if not self.is_deterministic:
diff --git a/paynt/quotient/pomdp.py b/paynt/quotient/pomdp.py
index 3bf1eb38..c725fe23 100644
--- a/paynt/quotient/pomdp.py
+++ b/paynt/quotient/pomdp.py
@@ -106,6 +106,9 @@ def __init__(self, pomdp, specification, decpomdp_manager=None):
                 else :
                     label = list(labels)[0]
                 self.action_labels_at_observation[obs].append(label)
+        for obs,labels in enumerate(self.action_labels_at_observation):
+            if len(labels) == 0:
+                logger.warning(f"WARNING: POMDP has no action for observation {obs}")
 
         # mark perfect observations
         self.observation_states = [0 for obs in range(self.observations)]