diff --git a/gklearn/model_learning/parameters.py b/gklearn/model_learning/parameters.py
new file mode 100644
index 0000000..b4c1d04
--- /dev/null
+++ b/gklearn/model_learning/parameters.py
@@ -0,0 +1,89 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+"""
+Created on Fri May 21 12:18:02 2021
+
+@author: ljia
+"""
+
+def dichotomous_permutation(arr, layer=0):
+	import math
+
+# 	def seperate_arr(arr, new_arr):
+# 		if (length % 2) == 0:
+# 			half = int(length / 2)
+# 			new_arr += [arr[half - 1], arr[half]]
+# 			subarr1 = [arr[i] for i in range(1, half - 1)]
+# 		else:
+# 			half = math.floor(length / 2)
+# 			new_arr.append(arr[half])
+# 			subarr1 = [arr[i] for i in range(1, half)]
+# 		subarr2 = [arr[i] for i in range(half + 1, length - 1)]
+# 		subarrs = [subarr1, subarr2]
+# 		return subarrs
+
+
+	if layer == 0:
+		length = len(arr)
+		if length <= 2:
+			return arr
+
+		new_arr = [arr[0], arr[-1]]
+		if (length % 2) == 0:
+ 			half = int(length / 2)
+ 			new_arr += [arr[half - 1], arr[half]]
+ 			subarr1 = [arr[i] for i in range(1, half - 1)]
+		else:
+ 			half = math.floor(length / 2)
+ 			new_arr.append(arr[half])
+ 			subarr1 = [arr[i] for i in range(1, half)]
+		subarr2 = [arr[i] for i in range(half + 1, length - 1)]
+		subarrs = [subarr1, subarr2]
+# 		subarrs = seperate_arr(arr, new_arr)
+		new_arr += dichotomous_permutation(subarrs, layer=layer+1)
+
+	else:
+		new_arr = []
+		subarrs = []
+		for a in arr:
+			length = len(a)
+			if length <= 2:
+				new_arr += a
+			else:
+# 				subarrs += seperate_arr(a, new_arr)
+				if (length % 2) == 0:
+ 					half = int(length / 2)
+ 					new_arr += [a[half - 1], a[half]]
+ 					subarr1 = [a[i] for i in range(0, half - 1)]
+				else:
+ 					half = math.floor(length / 2)
+ 					new_arr.append(a[half])
+ 					subarr1 = [a[i] for i in range(0, half)]
+				subarr2 = [a[i] for i in range(half + 1, length)]
+				subarrs += [subarr1, subarr2]
+
+		if len(subarrs) > 0:
+			new_arr += dichotomous_permutation(subarrs, layer=layer+1)
+
+	return new_arr
+
+# 	length = len(arr)
+# 	if length <= 2:
+# 		return arr
+
+# 	new_arr = [arr[0], arr[-1]]
+# 	if (length % 2) == 0:
+# 		half = int(length / 2)
+# 		new_arr += [arr[half - 1], arr[half]]
+# 		subarr1 = [arr[i] for i in range(1, half - 1)]
+# 	else:
+# 		half = math.floor(length / 2)
+# 		new_arr.append(arr[half])
+# 		subarr1 = [arr[i] for i in range(1, half)]
+# 	subarr2 = [arr[i] for i in range(half + 1, length - 1)]
+# 	if len(subarr1) > 0:
+# 		new_arr += dichotomous_permutation(subarr1)
+# 	if len(subarr2) > 0:
+# 		new_arr += dichotomous_permutation(subarr2)
+
+# 	return new_arr
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