diff --git a/kermit-ds/src/lib.rs b/kermit-ds/src/lib.rs
index 076b238..099fab7 100644
--- a/kermit-ds/src/lib.rs
+++ b/kermit-ds/src/lib.rs
@@ -1 +1,2 @@
+pub mod relation;
 pub mod relation_trie;
diff --git a/kermit-ds/src/relation.rs b/kermit-ds/src/relation.rs
new file mode 100644
index 0000000..d99b267
--- /dev/null
+++ b/kermit-ds/src/relation.rs
@@ -0,0 +1,9 @@
+pub trait Relation<KT>
+where
+    KT: PartialOrd + PartialEq + Clone,
+{
+    fn cardinality(&self) -> usize;
+    fn insert(&mut self, tuple: Vec<KT>) -> bool;
+    fn insert_all(&mut self, tuples: Vec<Vec<KT>>) -> bool;
+    fn from_tuples(cardinality: usize, tuples: Vec<Vec<KT>>) -> Self;
+}
diff --git a/kermit-ds/src/relation_trie/mod.rs b/kermit-ds/src/relation_trie/mod.rs
index f159410..827dcf2 100644
--- a/kermit-ds/src/relation_trie/mod.rs
+++ b/kermit-ds/src/relation_trie/mod.rs
@@ -7,7 +7,10 @@ pub mod variable_type;
 #[cfg(test)]
 mod tests {
     use {
-        crate::relation_trie::{node::TrieFields, trie::RelationTrie, trie_builder::TrieBuilder},
+        crate::{
+            relation::Relation,
+            relation_trie::{node::TrieFields, trie::RelationTrie, trie_builder::TrieBuilder},
+        },
         kermit_iters::{
             linear::LinearIterator,
             trie::{TrieIterable, TrieIterator},
diff --git a/kermit-ds/src/relation_trie/node.rs b/kermit-ds/src/relation_trie/node.rs
index 85aa5fc..4986850 100644
--- a/kermit-ds/src/relation_trie/node.rs
+++ b/kermit-ds/src/relation_trie/node.rs
@@ -74,9 +74,9 @@ where
 {
     fn children_mut(&mut self) -> &mut Vec<Node<KT>>;
 
-    fn insert_internal(&mut self, tuple: Vec<KT>) {
+    fn insert_internal(&mut self, tuple: Vec<KT>) -> bool {
         if tuple.is_empty() {
-            return;
+            return true;
         }
 
         let mut current_children = self.children_mut();
@@ -108,6 +108,7 @@ where
                 }
             }
         }
+        true
     }
 }
 
diff --git a/kermit-ds/src/relation_trie/trie.rs b/kermit-ds/src/relation_trie/trie.rs
index 22cd398..5fe2915 100644
--- a/kermit-ds/src/relation_trie/trie.rs
+++ b/kermit-ds/src/relation_trie/trie.rs
@@ -1,4 +1,7 @@
-use crate::relation_trie::node::{Internal, Node, TrieFields};
+use crate::{
+    relation::Relation,
+    relation_trie::node::{Internal, Node, TrieFields},
+};
 
 /// Trie data structure for relations.
 #[derive(Clone, Debug)]
@@ -12,14 +15,38 @@ where
     children: Vec<Node<KT>>,
 }
 
+impl<KT> Relation<KT> for RelationTrie<KT>
+where
+    KT: PartialOrd + PartialEq + Clone,
+{
+    fn cardinality(&self) -> usize { self.cardinality }
+
+    fn insert(&mut self, tuple: Vec<KT>) -> bool {
+        if tuple.len() != self.cardinality {
+            panic!("Arity doesn't match.");
+        }
+        self.insert_internal(tuple)
+    }
+
+    fn insert_all(&mut self, tuples: Vec<Vec<KT>>) -> bool {
+        for tuple in tuples {
+            if !self.insert(tuple) {
+                panic!("Failed to insert tuple.")
+            }
+        }
+        true
+    }
+
+    fn from_tuples(cardinality: usize, tuples: Vec<Vec<KT>>) -> Self {
+        RelationTrie::from_mut_tuples(cardinality, tuples)
+    }
+}
+
 /// Trie implementation.
 impl<KT> RelationTrie<KT>
 where
     KT: PartialOrd + PartialEq + Clone,
 {
-    /// Cardinality of the trie's relations.
-    pub fn cardinality(&self) -> usize { self.cardinality }
-
     /// Construct an empty Trie.
     ///
     /// # Panics
@@ -40,7 +67,9 @@ where
         assert!(tuples.iter().all(|tuple| tuple.len() == cardinality));
         let mut trie = RelationTrie::new(cardinality);
         for tuple in tuples {
-            trie.insert(tuple).unwrap();
+            if !trie.insert(tuple) {
+                panic!("Failed to build from tuples.");
+            }
         }
         trie
     }
@@ -66,15 +95,6 @@ where
         });
         RelationTrie::from_tuples(cardinality, tuples)
     }
-
-    /// Insert a tuple into the Trie.
-    pub fn insert(&mut self, tuple: Vec<KT>) -> Result<(), &'static str> {
-        if tuple.len() != self.cardinality {
-            return Err("Arity doesn't match.");
-        }
-        self.insert_internal(tuple);
-        Ok(())
-    }
 }
 
 impl<KT: PartialOrd + PartialEq + Clone> TrieFields<KT> for RelationTrie<KT> {