diff --git a/gemla/src/bin/test_state/mod.rs b/gemla/src/bin/test_state/mod.rs
index 4b9d994..329a172 100644
--- a/gemla/src/bin/test_state/mod.rs
+++ b/gemla/src/bin/test_state/mod.rs
@@ -1,19 +1,20 @@
-use rand::prelude::*;
-use rand::rngs::ThreadRng;
 use gemla::bracket::genetic_node::GeneticNode;
 use gemla::error;
+use rand::prelude::*;
+use rand::rngs::ThreadRng;
 use std::convert::TryInto;
 
 const POPULATION_SIZE: u64 = 5;
+const POPULATION_REDUCTION_SIZE: u64 = 3;
 
 struct TestState {
     pub population: Vec<f64>,
-    thread_rng: ThreadRng
+    thread_rng: ThreadRng,
 }
 
 impl GeneticNode for TestState {
     fn initialize() -> Result<Box<Self>, error::Error> {
-        let mut thread_rng = rand::thread_rng();
+        let mut thread_rng = thread_rng();
         let mut population: Vec<f64> = vec![];
 
         for _ in 0..POPULATION_SIZE {
@@ -22,28 +23,38 @@ impl GeneticNode for TestState {
 
         Ok(Box::new(TestState {
             population,
-            thread_rng
+            thread_rng,
         }))
     }
 
     fn simulate(&mut self, iterations: u64) -> Result<(), error::Error> {
         for _ in 0..iterations {
-            self.population = self.population.clone().iter().map(|p| p + self.thread_rng.gen_range(-10.0..10.0)).collect()
+            self.population = self
+                .population
+                .clone()
+                .iter()
+                .map(|p| p + self.thread_rng.gen_range(-10.0..10.0))
+                .collect()
         }
 
         Ok(())
     }
 
     fn get_fit_score(&self) -> f64 {
-        self.population.clone().into_iter().reduce(f64::max).unwrap()
+        self.population
+            .clone()
+            .into_iter()
+            .reduce(f64::max)
+            .unwrap()
     }
 
     fn calculate_scores_and_trim(&mut self) -> Result<(), error::Error> {
         let mut v = self.population.clone();
 
         v.sort_by(|a, b| a.partial_cmp(b).unwrap());
+        v.reverse();
 
-        self.population = v[4..].to_vec();
+        self.population = v[0..(POPULATION_REDUCTION_SIZE as usize)].to_vec();
 
         Ok(())
     }
@@ -56,7 +67,7 @@ impl GeneticNode for TestState {
 
             let new_individual_index = self.thread_rng.gen_range(0..self.population.len());
             let mut cross_breed_index = self.thread_rng.gen_range(0..self.population.len());
-            
+
             loop {
                 if new_individual_index != cross_breed_index {
                     break;
@@ -67,7 +78,7 @@ impl GeneticNode for TestState {
 
             let mut new_individual = self.population.clone()[new_individual_index];
             let cross_breed = self.population.clone()[cross_breed_index];
-            
+
             new_individual += cross_breed + self.thread_rng.gen_range(-10.0..10.0);
 
             self.population.push(new_individual);
@@ -75,4 +86,23 @@ impl GeneticNode for TestState {
 
         Ok(())
     }
-}
\ No newline at end of file
+
+    fn merge(left: &TestState, right: &TestState) -> Result<Box<TestState>, error::Error> {
+        let mut v = left.population.clone();
+        v.append(&mut right.population.clone());
+
+        v.sort_by(|a, b| a.partial_cmp(b).unwrap());
+        v.reverse();
+
+        v = v[..(POPULATION_REDUCTION_SIZE as usize)].to_vec();
+
+        let mut result = TestState {
+            population: v,
+            thread_rng: thread_rng(),
+        };
+
+        result.mutate()?;
+
+        Ok(Box::new(result))
+    }
+}
diff --git a/gemla/src/bracket/genetic_node.rs b/gemla/src/bracket/genetic_node.rs
index 3c9e4b4..9875d14 100644
--- a/gemla/src/bracket/genetic_node.rs
+++ b/gemla/src/bracket/genetic_node.rs
@@ -43,7 +43,7 @@ pub trait GeneticNode {
     /// }
     ///
     /// impl GeneticNode for Node {
-    ///     fn initialize() -> Result<Box<Self>, Error> {
+    ///     fn initialize() -> Result<Box<Node>, Error> {
     ///         Ok(Box::new(Node {fit_score: 0.0}))
     ///     }
     ///
@@ -64,6 +64,10 @@ pub trait GeneticNode {
     /// #   fn mutate(&mut self) -> Result<(), Error> {
     /// #       Ok(())
     /// #   }
+    /// #
+    /// #   fn merge(left: &Node, right: &Node) -> Result<Box<Node>, Error> {
+    /// #       Ok(Box::new(Node {fit_score: 0.0}))
+    /// #   }
     /// }
     ///
     /// # fn main() -> Result<(), Error> {
@@ -102,7 +106,7 @@ pub trait GeneticNode {
     /// }
     ///    
     /// impl GeneticNode for Node {
-    /// #    fn initialize() -> Result<Box<Self>, Error> {
+    /// #    fn initialize() -> Result<Box<Node>, Error> {
     /// #        Ok(Box::new(Node {models: vec![Model {fit_score: 0.0}]}))
     /// #    }
     /// #
@@ -129,6 +133,10 @@ pub trait GeneticNode {
     /// #    fn mutate(&mut self) -> Result<(), Error> {
     /// #        Ok(())
     /// #    }
+    /// #
+    /// #   fn merge(left: &Node, right: &Node) -> Result<Box<Node>, Error> {
+    /// #       Ok(Box::new(Node {models: vec![Model {fit_score: 0.0}]}))
+    /// #   }
     /// }
     ///    
     /// # fn main() -> Result<(), Error> {
@@ -167,7 +175,7 @@ pub trait GeneticNode {
     /// # }
     ///    
     /// impl GeneticNode for Node {
-    /// #    fn initialize() -> Result<Box<Self>, Error> {
+    /// #    fn initialize() -> Result<Box<Node>, Error> {
     /// #        Ok(Box::new(Node {models: vec![Model {fit_score: 0.0}]}))
     /// #    }
     /// #
@@ -195,6 +203,10 @@ pub trait GeneticNode {
     /// #    fn mutate(&mut self) -> Result<(), Error> {
     /// #        Ok(())
     /// #    }
+    /// #
+    /// #   fn merge(left: &Node, right: &Node) -> Result<Box<Node>, Error> {
+    /// #       Ok(Box::new(Node {models: vec![Model {fit_score: 0.0}]}))
+    /// #   }
     /// }
     ///    
     /// # fn main() -> Result<(), Error> {
@@ -233,7 +245,7 @@ pub trait GeneticNode {
     /// # }
     ///
     /// impl GeneticNode for Node {
-    /// #     fn initialize() -> Result<Box<Self>, Error> {
+    /// #     fn initialize() -> Result<Box<Node>, Error> {
     /// #         Ok(Box::new(Node {
     /// #             models: vec![
     /// #                 Model { fit_score: 0.0 },
@@ -276,6 +288,10 @@ pub trait GeneticNode {
     /// #     fn mutate(&mut self) -> Result<(), Error> {
     /// #         Ok(())
     /// #     }
+    /// #
+    /// #   fn merge(left: &Node, right: &Node) -> Result<Box<Node>, Error> {
+    /// #       Ok(Box::new(Node {models: vec![Model {fit_score: 0.0}], population_size: 1}))
+    /// #   }
     /// }
     ///
     /// # fn main() -> Result<(), Error> {
@@ -328,7 +344,7 @@ pub trait GeneticNode {
     /// }
     ///
     /// impl GeneticNode for Node {
-    /// #     fn initialize() -> Result<Box<Self>, Error> {
+    /// #     fn initialize() -> Result<Box<Node>, Error> {
     /// #         Ok(Box::new(Node {
     /// #             models: vec![
     /// #                 Model { fit_score: 0.0 },
@@ -374,6 +390,10 @@ pub trait GeneticNode {
     ///             }
     ///         }
     ///     }
+    /// #
+    /// #   fn merge(left: &Node, right: &Node) -> Result<Box<Node>, Error> {
+    /// #       Ok(Box::new(Node {models: vec![Model {fit_score: 0.0}], population_size: 1}))
+    /// #   }
     /// }
     ///
     /// # fn main() -> Result<(), Error> {
@@ -392,6 +412,8 @@ pub trait GeneticNode {
     /// # }
     /// ```
     fn mutate(&mut self) -> Result<(), Error>;
+
+    fn merge(left: &Self, right: &Self) -> Result<Box<Self>, Error>;
 }
 
 /// Used externally to wrap a node implementing the [`GeneticNode`] trait. Processes state transitions for the given node as
@@ -427,7 +449,7 @@ where
     ///
     /// impl GeneticNode for Node {
     ///     //...
-    /// #    fn initialize() -> Result<Box<Self>, Error> {
+    /// #    fn initialize() -> Result<Box<Node>, Error> {
     /// #        Ok(Box::new(Node {fit_score: 0.0}))
     /// #    }
     /// #
@@ -447,6 +469,10 @@ where
     /// #   fn mutate(&mut self) -> Result<(), Error> {
     /// #       Ok(())
     /// #   }
+    /// #
+    /// #   fn merge(left: &Node, right: &Node) -> Result<Box<Node>, Error> {
+    /// #       Ok(Box::new(Node {fit_score: 0.0}))
+    /// #   }
     /// }
     ///
     /// # fn main() -> Result<(), Error> {
diff --git a/gemla/src/bracket/mod.rs b/gemla/src/bracket/mod.rs
index 29804ca..82ecbda 100644
--- a/gemla/src/bracket/mod.rs
+++ b/gemla/src/bracket/mod.rs
@@ -59,6 +59,10 @@ use std::path;
 /// #     fn initialize() -> Result<Box<Self>, Error> {
 /// #         Ok(Box::new(TestState { score: 0.0 }))
 /// #     }
+/// #
+/// #     fn merge(left: &TestState, right: &TestState) -> Result<Box<Self>, Error> {
+/// #         Ok(Box::new(left.clone()))
+/// #     }
 /// # }
 /// #
 /// # fn main() {
@@ -176,6 +180,10 @@ where
     ///     }
     ///
     ///     //...
+    /// #
+    /// #     fn merge(left: &TestState, right: &TestState) -> Result<Box<Self>, Error> {
+    /// #         Ok(Box::new(left.clone()))
+    /// #     }
     /// }
     ///
     /// # fn main() {
@@ -245,6 +253,10 @@ where
     /// #     fn initialize() -> Result<Box<Self>, Error> {
     /// #         Ok(Box::new(TestState { score: 0.0 }))
     /// #     }
+    /// #
+    /// #     fn merge(left: &TestState, right: &TestState) -> Result<Box<Self>, Error> {
+    /// #         Ok(Box::new(left.clone()))
+    /// #     }
     /// # }
     /// #
     /// # fn main() {
@@ -353,6 +365,10 @@ where
     /// #     fn initialize() -> Result<Box<Self>, Error> {
     /// #         Ok(Box::new(TestState { score: 0.0 }))
     /// #     }
+    /// #
+    /// #     fn merge(left: &TestState, right: &TestState) -> Result<Box<Self>, Error> {
+    /// #         Ok(Box::new(left.clone()))
+    /// #     }
     /// # }
     /// #
     /// # fn main() {
@@ -442,9 +458,17 @@ mod tests {
             Ok(())
         }
 
-        fn initialize() -> Result<Box<Self>, Error> {
+        fn initialize() -> Result<Box<TestState>, Error> {
             Ok(Box::new(TestState { score: 0.0 }))
         }
+
+        fn merge(left: &TestState, right: &TestState) -> Result<Box<TestState>, Error> {
+            Ok(Box::new(if left.get_fit_score() > right.get_fit_score() {
+                left.clone()
+            } else {
+                right.clone()
+            }))
+        }
     }
 
     #[test]