diff --git a/book/src/SUMMARY.md b/book/src/SUMMARY.md
index a720c8a8..56d8b0c5 100644
--- a/book/src/SUMMARY.md
+++ b/book/src/SUMMARY.md
@@ -13,9 +13,11 @@
   - [Gadgets](user/gadgets.md)
   - [Tips and tricks](user/tips-and-tricks.md)
 - [Design](design.md)
-  - [Multipoint opening argument](design/multipoint-opening.md)
-  - [Permutation argument](design/permutation.md)
-  - [Lookup argument](design/lookup-argument.md)
+  - [Proving system](design/proving-system.md)
+    - [Multipoint opening argument](design/proving-system/multipoint-opening.md)
+    - [Permutation argument](design/proving-system/permutation.md)
+    - [Lookup argument](design/proving-system/lookup-argument.md)
+  - [Implementation](design/implementation.md)
   - [Gadgets](design/gadgets.md)
     - [SHA-256](design/gadgets/sha256.md)
       - [16-bit table chip](design/gadgets/sha256/table16.md)
diff --git a/book/src/design/implementation.md b/book/src/design/implementation.md
new file mode 100644
index 00000000..d2557ff7
--- /dev/null
+++ b/book/src/design/implementation.md
@@ -0,0 +1 @@
+# Implementation
diff --git a/book/src/design/proving-system.md b/book/src/design/proving-system.md
new file mode 100644
index 00000000..adad839e
--- /dev/null
+++ b/book/src/design/proving-system.md
@@ -0,0 +1 @@
+# Proving system
diff --git a/book/src/design/lookup-argument.md b/book/src/design/proving-system/lookup-argument.md
similarity index 100%
rename from book/src/design/lookup-argument.md
rename to book/src/design/proving-system/lookup-argument.md
diff --git a/book/src/design/multipoint-opening.md b/book/src/design/proving-system/multipoint-opening.md
similarity index 100%
rename from book/src/design/multipoint-opening.md
rename to book/src/design/proving-system/multipoint-opening.md
diff --git a/book/src/design/permutation.md b/book/src/design/proving-system/permutation.md
similarity index 100%
rename from book/src/design/permutation.md
rename to book/src/design/proving-system/permutation.md