Fixed _positive_roots_reflections for index_set different from {1, 2,…

… ..., n}
sagemath · Mar 1, 2025 · 19d5525 · 19d5525
1 parent 7ef5433
commit 19d5525
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/src/sage/groups/matrix_gps/coxeter_group.py b/src/sage/groups/matrix_gps/coxeter_group.py
@@ -557,13 +557,14 @@ def _positive_roots_reflections(self):
         simple_roots = FreeModule(self.base_ring(), self.ngens()).gens()
 
         refls = self.simple_reflections()
+        refls_index = dict((refl_i[1], refl_i[0]) for refl_i in enumerate(refls.keys()))
         resu = []
         d = {}
         for i in range(1, N + 1):
             segment = word[:i]
             last = segment.pop()
             ref = refls[last]
-            rt = simple_roots[last - 1]
+            rt = simple_roots[refls_index[last]]
             while segment:
                 last = segment.pop()
                 cr = refls[last]