bugfix!

CHANGELOG.md

@@ -4,6 +4,11 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
+## Unreleased
+
+### Fixed
+- Fixed bug in `Perm.rtlmax_ltrmin_decomposition` and fixed associated tests.
+
 ## 2.3.1 - 2025-06-13 
 ### Changed
  - Migrated from setup.py to modern pyproject.toml packaging with hatchling backend

permuta/patterns/perm.py

@@ -2451,7 +2451,7 @@ def count_rtlmax_ltrmin_layers(self) -> int:
 
         Examples:
             >>> Perm((2, 7, 3, 1, 4, 8, 6, 0, 5)).count_rtlmax_ltrmin_layers()
-            3
+            2
             >>> Perm((5, 4, 3, 0, 2, 1)).count_rtlmax_ltrmin_layers()
             1
         """
@@ -2468,15 +2468,17 @@ def rtlmax_ltrmin_decomposition(self) -> Iterator[List[int]]:
 
         Examples:
             >>> list(Perm((2, 7, 3, 1, 4, 8, 6, 0, 5)).rtlmax_ltrmin_decomposition())
-            [[0, 3, 5, 6, 7, 8], [0, 2], [0]]
+            [[0, 3, 5, 6, 7, 8], [0, 1, 2]]
             >>> list(Perm((5, 4, 3, 0, 2, 1)).rtlmax_ltrmin_decomposition())
             [[0, 1, 2, 3, 4, 5]]
         """
         perm = self
         while len(perm) > 0:
             pos_set = set(itertools.chain(perm.rtlmax(), perm.ltrmin()))
             yield sorted(pos_set)
-            perm = Perm(perm[i] for i in range(len(perm)) if i not in pos_set)
+            perm = Perm.to_standard(
+                perm[i] for i in range(len(perm)) if i not in pos_set
+            )
 
     def contains(self, *patts: "Patt") -> bool:
         """Check if self contains patts.

tests/patterns/test_perm.py

@@ -1966,15 +1966,15 @@ def test_count_rtlmax_ltrmin_layers():
     assert Perm((2, 1, 3, 0)).count_rtlmax_ltrmin_layers() == 1
     assert Perm((2, 0, 1, 3)).count_rtlmax_ltrmin_layers() == 2
     assert Perm((1, 3, 2, 7, 6, 5, 8, 0, 4)).count_rtlmax_ltrmin_layers() == 2
-    assert Perm((0, 8, 2, 4, 5, 6, 3, 7, 1)).count_rtlmax_ltrmin_layers() == 4
+    assert Perm((0, 8, 2, 4, 5, 6, 3, 7, 1)).count_rtlmax_ltrmin_layers() == 3
     assert Perm((1, 0, 2)).count_rtlmax_ltrmin_layers() == 1
     assert Perm((1, 2, 0, 3)).count_rtlmax_ltrmin_layers() == 2
     assert Perm((3, 0, 2, 1)).count_rtlmax_ltrmin_layers() == 1
     assert Perm((2, 0, 1)).count_rtlmax_ltrmin_layers() == 1
     assert Perm((1, 3, 2, 0)).count_rtlmax_ltrmin_layers() == 1
     assert Perm(()).count_rtlmax_ltrmin_layers() == 0
     assert Perm((5, 3, 7, 4, 2, 0, 6, 1)).count_rtlmax_ltrmin_layers() == 2
-    assert Perm((0, 2, 1, 6, 4, 3, 5, 7, 8)).count_rtlmax_ltrmin_layers() == 4
+    assert Perm((0, 2, 1, 6, 4, 3, 5, 7, 8)).count_rtlmax_ltrmin_layers() == 3
     assert Perm((2, 1, 0)).count_rtlmax_ltrmin_layers() == 1
     assert Perm((0, 2, 1)).count_rtlmax_ltrmin_layers() == 1
     assert Perm((0, 8, 3, 5, 7, 4, 2, 6, 1)).count_rtlmax_ltrmin_layers() == 2
@@ -2003,8 +2003,7 @@ def test_rtlmax_ltrmin_decomposition():
     ]
     assert list(Perm((2, 3, 0, 4, 1, 5)).rtlmax_ltrmin_decomposition()) == [
         [0, 2, 5],
-        [1, 2],
-        [0],
+        [0, 1, 2],
     ]
     assert list(Perm((4, 0, 2, 5, 3, 1)).rtlmax_ltrmin_decomposition()) == [
         [0, 1, 3, 4, 5],