diff --git a/model.py b/model.py
index 615e6ee..6272d48 100644
--- a/model.py
+++ b/model.py
@@ -129,6 +129,12 @@ class OrderTable:
 
         candidates = X.intersection(Y)
 
+        if not candidates:
+            return None
+
+        if len(candidates) == 1:
+            return next(iter(candidates))
+
         # Grab all elements greater than each of the candidates
         candidate_ge_maps = (self.ge_map[candidate] for candidate in candidates)
         common_ge_values = reduce(set.intersection, candidate_ge_maps)
@@ -147,6 +153,12 @@ class OrderTable:
 
         candidates = X.intersection(Y)
 
+        if not candidates:
+            return None
+
+        if len(candidates) == 1:
+            return next(iter(candidates))
+
         # Grab all elements smaller than each of the candidates
         candidate_le_maps = (self.le_map[candidate] for candidate in candidates)
         common_le_values = reduce(set.intersection, candidate_le_maps)