diff --git a/CMakeLists.txt b/CMakeLists.txt
index 46822a9..1aa6f62 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,5 +1,5 @@
 cmake_minimum_required(VERSION 3.25)
-project(blt-gp VERSION 0.0.140)
+project(blt-gp VERSION 0.0.141)
 
 include(CTest)
 
diff --git a/include/blt/gp/tree.h b/include/blt/gp/tree.h
index 841aed1..d1293ff 100644
--- a/include/blt/gp/tree.h
+++ b/include/blt/gp/tree.h
@@ -60,31 +60,6 @@ namespace blt::gp
     {
             using iter_type = std::vector<op_container_t>::const_iterator;
         public:
-            tree_t(): reference_counter(new std::atomic_int64_t(1))
-            {}
-            
-            tree_t(const tree_t& copy): operations(copy.operations), values(copy.values), reference_counter(copy.reference_counter)
-            {
-                reference_counter->operator++();
-            }
-            
-            tree_t(tree_t&& move) noexcept:
-                    operations(std::move(move.operations)), values(std::move(move.values)), reference_counter(move.reference_counter)
-            {
-                move.reference_counter = nullptr;
-            }
-            
-            tree_t& operator=(const tree_t& copy) = delete;
-            
-            tree_t& operator=(tree_t&& move) noexcept
-            {
-                operations = std::exchange(operations, std::move(move.operations));
-                values = std::exchange(values, std::move(move.values));
-                reference_counter = std::exchange(reference_counter, move.reference_counter);
-                return *this;
-            }
-            
-            
             [[nodiscard]] inline std::vector<op_container_t>& get_operations()
             {
                 return operations;
@@ -142,7 +117,8 @@ namespace blt::gp
             
             bool check(gp_program& program, void* context) const;
             
-            blt::ptrdiff_t find_endpoint(blt::gp::gp_program& program, blt::ptrdiff_t start);
+            blt::ptrdiff_t find_endpoint(blt::gp::gp_program& program, blt::ptrdiff_t start) const;
+            blt::ptrdiff_t find_parent(blt::gp::gp_program& program, blt::ptrdiff_t start) const;
             
             // valid for [begin, end)
             static blt::size_t total_value_bytes(iter_type begin, iter_type end)
@@ -173,16 +149,6 @@ namespace blt::gp
             }
             
             void drop(gp_program& program);
-            
-            ~tree_t()
-            {
-                if (reference_counter == nullptr)
-                    return;
-                reference_counter->operator--();
-                if (*reference_counter == 0)
-                    delete reference_counter;
-            }
-        
         private:
             std::vector<op_container_t> operations;
             blt::gp::stack_allocator values;
diff --git a/lib/blt b/lib/blt
index 644f426..6f06647 160000
--- a/lib/blt
+++ b/lib/blt
@@ -1 +1 @@
-Subproject commit 644f42684320edc95f9fd5fc3b203bda3c4e6633
+Subproject commit 6f06647a21f7f29e99ef8e45e1d3c08db0b46038
diff --git a/src/tree.cpp b/src/tree.cpp
index 5514847..4bbd49c 100644
--- a/src/tree.cpp
+++ b/src/tree.cpp
@@ -207,7 +207,7 @@ namespace blt::gp
         return depth;
     }
     
-    blt::ptrdiff_t tree_t::find_endpoint(gp_program& program, blt::ptrdiff_t index)
+    blt::ptrdiff_t tree_t::find_endpoint(gp_program& program, blt::ptrdiff_t index) const
     {
         blt::i64 children_left = 0;
         
@@ -225,6 +225,28 @@ namespace blt::gp
         return index;
     }
     
+    blt::ptrdiff_t tree_t::find_parent(gp_program& program, blt::ptrdiff_t index) const
+    {
+        if (index == 0)
+            return 0;
+        blt::i64 children_left = 1;
+        // move to the left
+        --index;
+        do
+        {
+            const auto& type = program.get_operator_info(operations[index].id);
+            BLT_TRACE_STREAM << "Operating on index " << index << " with children left: " << children_left << " and argc = " << type.argc.argc << "\n";
+            --index;
+            if (type.argc.argc > 0)
+                children_left -= type.argc.argc;
+            if (children_left <= 0)
+                break;
+            children_left++;
+        } while (children_left > 0);
+        
+        return index;
+    }
+    
     bool tree_t::check(gp_program& program, void* context) const
     {
         static thread_local detail::bitmask_t bitfield;