diff --git a/reference/algorithm/inplace_merge.md b/reference/algorithm/inplace_merge.md
index 72932b0df1..2af32581f8 100644
--- a/reference/algorithm/inplace_merge.md
+++ b/reference/algorithm/inplace_merge.md
@@ -9,12 +9,23 @@ namespace std {
   void inplace_merge(BidirectionalIterator first,
                      BidirectionalIterator middle,
                      BidirectionalIterator last);  // (1) C++03
+  template <class BidirectionalIterator>
+  constexpr
+  void inplace_merge(BidirectionalIterator first,
+                     BidirectionalIterator middle,
+                     BidirectionalIterator last);  // (1) C++26
 
   template <class BidirectionalIterator, class Compare>
   void inplace_merge(BidirectionalIterator first,
                      BidirectionalIterator middle,
                      BidirectionalIterator last,
                      Compare comp);                // (2) C++03
+  template <class BidirectionalIterator, class Compare>
+  constexpr
+  void inplace_merge(BidirectionalIterator first,
+                     BidirectionalIterator middle,
+                     BidirectionalIterator last,
+                     Compare comp);                // (2) C++26
 
   template <class ExecutionPolicy, class BidirectionalIterator>
   void inplace_merge(ExecutionPolicy&& exec,
@@ -94,7 +105,9 @@ int main()
 ```
 
 ## 実装例
-- [inplace_merge を読んでみた](http://www.kmonos.net/wlog/115.html#_2300101215)
-
+- [`inplace_merge` を読んでみた](http://www.kmonos.net/wlog/115.html#_2300101215)
 
 
+## 参照
+- [P2562R1 `constexpr` Stable Sorting](https://open-std.org/jtc1/sc22/wg21/docs/papers/2022/p2562r1.pdf)
+    - C++26から`constexpr`に対応した
diff --git a/reference/algorithm/ranges_inplace_merge.md b/reference/algorithm/ranges_inplace_merge.md
index 3b5b73f0cc..062a0e0a0f 100644
--- a/reference/algorithm/ranges_inplace_merge.md
+++ b/reference/algorithm/ranges_inplace_merge.md
@@ -17,6 +17,17 @@ namespace std::ranges {
                   S last,
                   Comp comp = {},
                   Proj proj = {}); // (1) C++20
+  template <bidirectional_iterator I,
+            sentinel_for<I> S,
+            class Comp = ranges::less,
+            class Proj = identity>
+    requires sortable<I, Comp, Proj>
+  constexpr I
+    inplace_merge(I first,
+                  I middle,
+                  S last,
+                  Comp comp = {},
+                  Proj proj = {}); // (1) C++26
 
   template <bidirectional_range R,
             class Comp = ranges::less,
@@ -27,6 +38,15 @@ namespace std::ranges {
                   iterator_t<R> middle,
                   Comp comp = {},
                   Proj proj = {}); // (2) C++20
+  template <bidirectional_range R,
+            class Comp = ranges::less,
+            class Proj = identity>
+    requires sortable<iterator_t<R>, Comp, Proj>
+  constexpr borrowed_iterator_t<R>
+    inplace_merge(R&& r,
+                  iterator_t<R> middle,
+                  Comp comp = {},
+                  Proj proj = {}); // (2) C++26
 }
 ```
 * bidirectional_iterator[link /reference/iterator/bidirectional_iterator.md]
@@ -98,7 +118,7 @@ int main()
 ```
 
 ## 実装例
-- [inplace_merge を読んでみた](http://www.kmonos.net/wlog/115.html#_2300101215)
+- [`inplace_merge` を読んでみた](http://www.kmonos.net/wlog/115.html#_2300101215)
 
 ## バージョン
 ### 言語
@@ -112,5 +132,5 @@ int main()
 
 ## 参照
 - [N4861 25 Algorithms library](https://timsong-cpp.github.io/cppwp/n4861/algorithms)
-
-
+- [P2562R1 `constexpr` Stable Sorting](https://open-std.org/jtc1/sc22/wg21/docs/papers/2022/p2562r1.pdf)
+    - C++26から`constexpr`に対応した
diff --git a/reference/algorithm/ranges_stable_partition.md b/reference/algorithm/ranges_stable_partition.md
index a2324e8770..5fd20f2956 100644
--- a/reference/algorithm/ranges_stable_partition.md
+++ b/reference/algorithm/ranges_stable_partition.md
@@ -16,6 +16,16 @@ namespace std::ranges {
                      S last,
                      Pred pred,
                      Proj proj = {}); // (1) C++20
+  template <bidirectional_iterator I,
+            sentinel_for<I> S,
+            class Proj = identity,
+            indirect_unary_predicate<projected<I, Proj>> Pred>
+    requires permutable<I>
+  constexpr subrange<I>
+    stable_partition(I first,
+                     S last,
+                     Pred pred,
+                     Proj proj = {}); // (1) C++26
 
   template <bidirectional_range R,
             class Proj = identity,
@@ -25,6 +35,14 @@ namespace std::ranges {
     stable_partition(R&& r,
                      Pred pred,
                      Proj proj = {}); // (2) C++20
+  template <bidirectional_range R,
+            class Proj = identity,
+            indirect_unary_predicate<projected<iterator_t<R>, Proj>> Pred>
+    requires permutable<iterator_t<R>>
+  constexpr borrowed_subrange_t<R>
+    stable_partition(R&& r,
+                     Pred pred,
+                     Proj proj = {}); // (2) C++26
 }
 ```
 * bidirectional_iterator[link /reference/iterator/bidirectional_iterator.md]
@@ -106,3 +124,5 @@ int main()
 
 ## 参照
 - [N4861 25 Algorithms library](https://timsong-cpp.github.io/cppwp/n4861/algorithms)
+- [P2562R1 `constexpr` Stable Sorting](https://open-std.org/jtc1/sc22/wg21/docs/papers/2022/p2562r1.pdf)
+    - C++26から`constexpr`に対応した
diff --git a/reference/algorithm/ranges_stable_sort.md b/reference/algorithm/ranges_stable_sort.md
index e0c93a7f7e..bde206d5cd 100644
--- a/reference/algorithm/ranges_stable_sort.md
+++ b/reference/algorithm/ranges_stable_sort.md
@@ -16,6 +16,16 @@ namespace std::ranges {
                 S last,
                 Comp comp = {},
                 Proj proj = {}); // (1) C++20
+  template <random_access_iterator I,
+            sentinel_for<I> S,
+            class Comp = ranges::less,
+            class Proj = identity>
+    requires sortable<I, Comp, Proj>
+  constexpr I
+    stable_sort(I first,
+                S last,
+                Comp comp = {},
+                Proj proj = {}); // (1) C++26
 
   template <random_access_range R,
             class Comp = ranges::less,
@@ -25,6 +35,14 @@ namespace std::ranges {
     stable_sort(R&& r,
                 Comp comp = {},
                 Proj proj = {}); // (2) C++20
+  template <random_access_range R,
+            class Comp = ranges::less,
+            class Proj = identity>
+    requires sortable<iterator_t<R>, Comp, Proj>
+  constexpr borrowed_iterator_t<R>
+    stable_sort(R&& r,
+                Comp comp = {},
+                Proj proj = {}); // (2) C++26
 }
 ```
 * random_access_iterator[link /reference/iterator/random_access_iterator.md]
@@ -96,3 +114,5 @@ int main()
 
 ## 参照
 - [N4861 25 Algorithms library](https://timsong-cpp.github.io/cppwp/n4861/algorithms)
+- [P2562R1 `constexpr` Stable Sorting](https://open-std.org/jtc1/sc22/wg21/docs/papers/2022/p2562r1.pdf)
+    - C++26から`constexpr`に対応した
diff --git a/reference/algorithm/stable_partition.md b/reference/algorithm/stable_partition.md
index 38d2af6d84..1ab0fc7da5 100644
--- a/reference/algorithm/stable_partition.md
+++ b/reference/algorithm/stable_partition.md
@@ -10,6 +10,11 @@ namespace std {
     stable_partition(BidirectionalIterator first,
                      BidirectionalIterator last,
                      Predicate pred);             // (1) C++03
+  template<class BidirectionalIterator, class Predicate>
+  constexpr BidirectionalIterator
+    stable_partition(BidirectionalIterator first,
+                     BidirectionalIterator last,
+                     Predicate pred);             // (1) C++26
 
   template <class ExecutionPolicy, class BidirectionalIterator, class Predicate>
   BidirectionalIterator
@@ -81,3 +86,5 @@ int main()
 ## 参照
 - [LWG Issue 2150. Unclear specification of `find_end`](http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#2150)
 - [P0574R1 Algorithm Complexity Constraints and Parallel Overloads](http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0574r1.html)
+- [P2562R1 `constexpr` Stable Sorting](https://open-std.org/jtc1/sc22/wg21/docs/papers/2022/p2562r1.pdf)
+    - C++26から`constexpr`に対応した
diff --git a/reference/algorithm/stable_sort.md b/reference/algorithm/stable_sort.md
index 0f77c873be..f66fe2166b 100644
--- a/reference/algorithm/stable_sort.md
+++ b/reference/algorithm/stable_sort.md
@@ -7,12 +7,21 @@
 namespace std {
   template <class RandomAccessIterator>
   void stable_sort(RandomAccessIterator first,
-                  RandomAccessIterator last);  // (1) C++03
+                   RandomAccessIterator last);  // (1) C++03
+  template <class RandomAccessIterator>
+  constexpr
+  void stable_sort(RandomAccessIterator first,
+                   RandomAccessIterator last);  // (1) C++26
 
   template <class RandomAccessIterator, class Compare>
   void stable_sort(RandomAccessIterator first,
                    RandomAccessIterator last,
                    Compare comp);              // (2) C++03
+  template <class RandomAccessIterator, class Compare>
+  constexpr
+  void stable_sort(RandomAccessIterator first,
+                   RandomAccessIterator last,
+                   Compare comp);              // (2) C++26
 
   template<class ExecutionPolicy, class RandomAccessIterator>
   void stable_sort(ExecutionPolicy&& exec,
@@ -82,3 +91,7 @@ int main()
 5
 ```
 
+
+## 参照
+- [P2562R1 `constexpr` Stable Sorting](https://open-std.org/jtc1/sc22/wg21/docs/papers/2022/p2562r1.pdf)
+    - C++26から`constexpr`に対応した