diff --git a/.gitmodules b/.gitmodules
index ba212b8..4bb22f0 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -32,3 +32,6 @@
 [submodule "gtrr"]
 	path = gtrr
 	url = https://github.com/artemislena/gtrr
+[submodule "relax"]
+	path = relax
+	url = https://github.com/dbis-uibk/relax
diff --git a/relax b/relax
new file mode 160000
index 0000000..252d0d5
--- /dev/null
+++ b/relax
@@ -0,0 +1 @@
+Subproject commit 252d0d5c705112fc3cc6f53ad43e8431672ccd2e