From 3064fbdd357f0c7f22d6eb5d8c18d53ccdd4198d Mon Sep 17 00:00:00 2001
From: ZhengLi <zhengli0060@gmail.com>
Date: Fri, 5 Sep 2025 15:58:09 +0800
Subject: [PATCH] Fix bug: rule9-uncovered p.d. paths

Signed-off-by: Zheng Li <zhengli0060@gmail.com>
---
 causallearn/search/ConstraintBased/FCI.py | 51 ++++++++++++++++++++++-
 tests/TestDAG2PAG.py                      | 37 ++++++++++++++++
 2 files changed, 87 insertions(+), 1 deletion(-)

diff --git a/causallearn/search/ConstraintBased/FCI.py b/causallearn/search/ConstraintBased/FCI.py
index 43d1e29..869b8de 100644
--- a/causallearn/search/ConstraintBased/FCI.py
+++ b/causallearn/search/ConstraintBased/FCI.py
@@ -82,6 +82,54 @@ def existsSemiDirectedPath(node_from: Node, node_to: Node, G: Graph) -> bool: ##
 
     return False
 
+
+
+def traversePotentiallyDirected(node: Node, edge: Edge) -> Node | None:
+    if node == edge.get_node1():
+        if (edge.get_endpoint1() == Endpoint.TAIL or edge.get_endpoint1() == Endpoint.CIRCLE) and \
+            (edge.get_endpoint2() == Endpoint.ARROW or edge.get_endpoint2() == Endpoint.CIRCLE):
+            return edge.get_node2()
+    elif node == edge.get_node2():
+        if (edge.get_endpoint2() == Endpoint.TAIL or edge.get_endpoint2() == Endpoint.CIRCLE) and \
+            (edge.get_endpoint1() == Endpoint.ARROW or edge.get_endpoint1() == Endpoint.CIRCLE):
+            return edge.get_node1()
+    return None
+
+
+def existsUncoveredPdPath(node_from: Node, node_next: Node, node_to: Node, G: Graph) -> bool:
+    Q = Queue()
+    V = set([node_from, node_next])
+
+    for node_u in G.get_adjacent_nodes(node_next):
+        edge = G.get_edge(node_next, node_u)
+        node_c = traversePotentiallyDirected(node_next, edge)
+
+        if node_c is None:
+            continue
+
+        if not V.__contains__(node_c):
+            V.add(node_c)
+            Q.put((node_c, [node_from, node_next, node_c]))
+
+    while not Q.empty():
+        node_t, path = Q.get_nowait()
+        if node_t == node_to and is_uncovered_path(path, G):
+            # print(f"Found uncovered pd path: {[node.get_name() for node in path]}")
+            return True
+
+        for node_u in G.get_adjacent_nodes(node_t):
+            edge = G.get_edge(node_t, node_u)
+            node_c = traversePotentiallyDirected(node_t, edge)
+
+            if node_c is None:
+                continue
+
+            if not V.__contains__(node_c):
+                V.add(node_c)
+                Q.put((node_c, path + [node_c]))
+
+    return False
+
 def GetUncoveredCirclePath(node_from: Node, node_to: Node, G: Graph, exclude_node: List[Node]) -> Generator[Node] | None:
     Q = Queue()
     V = set()
@@ -802,7 +850,8 @@ def rule9(graph: Graph, nodes: List[Node], changeFlag):
             for node_B in possible_children:
                 if graph.is_adjacent_to(node_B, node_C):
                     continue
-                if existsSemiDirectedPath(node_from=node_B, node_to=node_C, G=graph):
+
+                if existsUncoveredPdPath(node_from=node_A, node_next=node_B, node_to=node_C, G=graph):
                     edge1 = graph.get_edge(node_A, node_C)
                     graph.remove_edge(edge1)
                     graph.add_edge(Edge(node_A, node_C, Endpoint.TAIL, Endpoint.ARROW))
diff --git a/tests/TestDAG2PAG.py b/tests/TestDAG2PAG.py
index 004ea89..495231e 100644
--- a/tests/TestDAG2PAG.py
+++ b/tests/TestDAG2PAG.py
@@ -86,3 +86,40 @@ def test_case_selection(self):
         dag.add_directed_edge(nodes[0], nodes[4])
         pag = dag2pag(dag, islatent=[], isselection=[nodes[4]])
         print(pag)
+
+    def test_case_orient_rules(self):
+        nodes = []
+        X = {}
+        L = {}
+        for i in range(7):
+            node_name = f"X{i + 1}"
+            if i + 1 == 2:
+                node_name = f"L{i + 1}"
+            node = GraphNode(node_name)
+            nodes.append(node)
+            if i + 1 == 2:
+                L[2] = node
+            else:
+                X[i + 1] = node
+        dag = Dag(nodes)
+        dag.add_directed_edge(L[2], X[4])
+        dag.add_directed_edge(L[2], X[5])   
+        dag.add_directed_edge(L[2], X[6])
+
+        dag.add_directed_edge(X[5], X[7])
+        dag.add_directed_edge(X[1], X[4])
+        dag.add_directed_edge(X[1], X[7])
+        dag.add_directed_edge(X[3], X[7])   
+        pag = dag2pag(dag, [L[2]])
+        print(pag)
+        graphviz_pag = GraphUtils.to_pgv(pag)
+        graphviz_pag.draw("pag.png", prog='dot', format='png')
+
+
+if __name__ == "__main__":
+    test_model = TestDAG2PAG()
+    test_model.test_case1()
+    test_model.test_case2()
+    test_model.test_case3()
+    test_model.test_case_selection()
+    test_model.test_case_orient_rules()
\ No newline at end of file