diff --git a/planner/src/bin/weekly.rs b/planner/src/bin/weekly.rs
index 22289d4..b5b6e92 100644
--- a/planner/src/bin/weekly.rs
+++ b/planner/src/bin/weekly.rs
@@ -5,7 +5,11 @@ extern crate planner;
 
 use self::cookbook::*;
 use self::cookbook::models::Recipe;
-use self::planner::solver::{Domain, Problem, Variables};
+use self::planner::solver::{Domain, Problem, Constraint, Variables};
+
+/// We want a mapping of the week meals (matin, midi, soir)
+/// associated with filters for Domain, depending on recipes RecipeCategory
+/// It may also contains an initial value for each variable
 
 fn ingredients_contains<'a>(assign: &Variables<'a,Recipe>) -> bool {
        assign.get("Lundi_midi").unwrap().unwrap().ingredients.contains("Patates")
@@ -16,18 +20,15 @@ fn get_planning_all_results() -> String {
     let conn = establish_connection();
     let possible_values = recipes::load_all(&conn);
     let domain = Domain::new(possible_values);
-
     let mut problem = Problem::build()
         .add_variable("Lundi_midi".to_string(), &domain, None)
         .add_variable("Mardi_midi".to_string(), &domain, None)
         .add_constraint(ingredients_contains)
         .finish();
-
     let results = problem.solve_all();
     format!("{:#?}\nTotal = {}", &results, results.len())
 }
 
 fn main() {
-
     println!("{}", get_planning_all_results());
 }
diff --git a/planner/src/solver.rs b/planner/src/solver.rs
index c041869..d70206e 100644
--- a/planner/src/solver.rs
+++ b/planner/src/solver.rs
@@ -17,13 +17,32 @@ enum Assignment<'a, V> {
 /// The domain of values that can be assigned to variables
 #[derive(Clone)]
 pub struct Domain<V> {
-    values: Vec<V>
+    pub values: Vec<V>
 }
 
 impl<V> Domain<V> {
     pub fn new(values: Vec<V>) -> Domain<V> {
         Domain { values }
     }
+
+    /// Returns a new domain with the given filter applied to inner values
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # extern crate planner;
+    /// # use planner::solver::Domain;
+    /// let domain = Domain::new(vec![1,2,3]);
+    /// fn even(i: &i32) -> bool { i % 2 == 0 };
+    /// assert_eq!(&domain.filter(even).values, &vec![2]);
+    /// ```
+    pub fn filter(&self, f: fn(&V) -> bool) -> Domain<V>
+        where V: std::clone::Clone
+    {
+        Domain {
+            values: self.values.iter().cloned().filter(f).collect(),
+        }
+    }
 }
 
 impl<V: fmt::Debug> fmt::Debug for Domain<V> {
@@ -32,7 +51,7 @@ impl<V: fmt::Debug> fmt::Debug for Domain<V> {
     }
 }
 
-type Constraint<'a,V> = fn(&Variables<'a,V>) -> bool;
+pub type Constraint<'a,V> = fn(&Variables<'a,V>) -> bool;
 
 pub struct Problem<'a, V> {
     /// The initial assignements map