diff --git a/doz/src/constraint.rs b/doz/src/constraint.rs
new file mode 100644
index 0000000..5e805a7
--- /dev/null
+++ b/doz/src/constraint.rs
@@ -0,0 +1,103 @@
+pub mod resolution;
+
+use std::collections::{HashMap, VecDeque};
+
+use crate::domain::{Domain, DomainRange};
+
+pub struct Indexical
+{
+    pub variable: usize,
+    pub dependencies: Vec<usize>,
+
+    #[allow(clippy::type_complexity)]
+    pub propagator: Box<dyn Fn(&[DomainRange]) -> DomainRange>,
+}
+
+impl Indexical
+{
+    pub fn new<T>(variable: usize, dependencies: &[usize], propagator: T) -> Indexical
+    where
+        T: Fn(&[DomainRange]) -> DomainRange + 'static,
+    {
+        Indexical {
+            variable,
+            dependencies: dependencies.to_vec(),
+            propagator: Box::new(propagator),
+        }
+    }
+}
+
+pub struct ClpContext
+{
+    pub variables: usize,
+    pub domains: HashMap<usize, Domain>,
+    pub used_by: HashMap<usize, Vec<usize>>,
+    pub constraints: HashMap<usize, Vec<Indexical>>,
+}
+
+impl ClpContext
+{
+    pub fn new() -> Self
+    {
+        ClpContext {
+            variables: 0,
+            domains: HashMap::new(),
+            used_by: HashMap::new(),
+            constraints: HashMap::new(),
+        }
+    }
+
+    pub fn get_var(&mut self) -> usize
+    {
+        let k = self.variables;
+        self.variables += 1;
+        self.domains.insert(k, Domain::from(..));
+        self.used_by.insert(k, vec![]);
+        k
+    }
+
+    pub fn insert_constraint(&mut self, indexical: Indexical)
+    {
+        let vec = self.constraints.entry(indexical.variable).or_insert(vec![]);
+        for x in indexical.dependencies.iter()
+        {
+            self.used_by.get_mut(x).unwrap().push(indexical.variable);
+        }
+        vec.push(indexical);
+    }
+
+    pub fn prune(&mut self) -> bool
+    {
+        let mut queue = VecDeque::from_iter(0..self.variables);
+
+        while !queue.is_empty()
+        {
+            // Apply unary constraints
+            let var = queue.pop_front().unwrap();
+            let constraints = self.constraints.get(&var);
+            if constraints.is_none()
+            {
+                continue;
+            }
+            let constraints = constraints.unwrap();
+
+            for c in constraints.iter()
+            {
+                if c.dependencies.is_empty()
+                {
+                    // Is unary constraint
+                    let domain = self.domains.get(&var).unwrap();
+                }
+            }
+        }
+        todo!();
+    }
+}
+
+impl Default for ClpContext
+{
+    fn default() -> Self
+    {
+        Self::new()
+    }
+}
diff --git a/doz/src/constraint/resolution.rs b/doz/src/constraint/resolution.rs
new file mode 100644
index 0000000..e69de29
diff --git a/doz/src/domain.rs b/doz/src/domain.rs
index 09aefe2..7176cb8 100644
--- a/doz/src/domain.rs
+++ b/doz/src/domain.rs
@@ -1,9 +1,10 @@
-pub mod simple_range;
-pub mod union;
+pub mod domain_ops;
+pub mod range_ops;
 
 use std::fmt::Display;
 use std::ops::Range;
 use std::ops::RangeFrom;
+use std::ops::RangeFull;
 use std::ops::RangeTo;
 
 pub struct Domain
@@ -15,16 +16,6 @@ pub struct Domain
 /// $$\{x \in [\text{start}; \text{end}[ | x \equiv \text{congruent} \text{mod} \text{modulo}}$$
 #[derive(Clone, Copy, PartialEq, Eq, Debug)]
 pub struct DomainRange
-{
-    pub start: LowerBound,
-    pub end: HigherBound,
-
-    pub modulo: u64,
-    pub congruent: i64,
-}
-
-#[derive(Clone, Copy, PartialEq, Eq, Debug)]
-pub struct SimpleRange
 {
     pub start: LowerBound,
     pub end: HigherBound,
@@ -70,23 +61,6 @@ impl DomainRange
         DomainRange {
             start: from,
             end: to,
-            modulo: 1,
-            congruent: 0,
-        }
-    }
-
-    pub fn is_simple(&self) -> Option<SimpleRange>
-    {
-        if self.modulo <= 1
-        {
-            Some(SimpleRange {
-                start: self.start,
-                end: self.end,
-            })
-        }
-        else
-        {
-            None
         }
     }
 }
@@ -101,6 +75,16 @@ impl From<Range<i64>> for Domain
     }
 }
 
+impl From<RangeFull> for Domain
+{
+    fn from(value: RangeFull) -> Self
+    {
+        Domain {
+            ranges: vec![value.into()],
+        }
+    }
+}
+
 impl From<RangeTo<i64>> for Domain
 {
     fn from(value: RangeTo<i64>) -> Self
@@ -148,6 +132,14 @@ impl From<RangeFrom<i64>> for DomainRange
     }
 }
 
+impl From<RangeFull> for DomainRange
+{
+    fn from(_: RangeFull) -> Self
+    {
+        DomainRange::range(LowerBound::Infinity, HigherBound::Infinity)
+    }
+}
+
 impl Display for LowerBound
 {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result
@@ -176,12 +168,7 @@ impl Display for DomainRange
 {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result
     {
-        write!(f, "{}..{}", self.start, self.end)?;
-        if self.modulo > 1
-        {
-            write!(f, " ≡ {} [{}]", self.congruent, self.modulo)?;
-        }
-        Ok(())
+        write!(f, "{}..{}", self.start, self.end)
     }
 }
 
diff --git a/doz/src/domain/domain_ops.rs b/doz/src/domain/domain_ops.rs
new file mode 100644
index 0000000..60f1e36
--- /dev/null
+++ b/doz/src/domain/domain_ops.rs
@@ -0,0 +1,90 @@
+use crate::domain::{Domain, DomainRange};
+
+impl Domain
+{
+    pub fn intersection(&self, domain: &Domain) -> Domain
+    {
+        let mut i = 0;
+        let mut j = 0;
+        let mut stack = vec![];
+
+        while i < self.ranges.len() || j < domain.ranges.len()
+        {
+            if i < self.ranges.len() && j < domain.ranges.len()
+            {
+                let a = self.ranges[i];
+                let b = domain.ranges[j];
+
+                if a.disjoint(&b)
+                {
+                    if a.start < b.start
+                    {
+                        i += 1;
+                    }
+                    else
+                    {
+                        j += 1;
+                    }
+                }
+                else
+                {
+                    let inter = a.intersection(&b);
+                    if let Some(range) = inter
+                    {
+                        stack.push(range);
+                    };
+                    if a.end > b.end
+                    {
+                        i += 1;
+                    }
+                    else
+                    {
+                        j += 1;
+                    }
+                }
+            }
+            else
+            {
+                break;
+            }
+        }
+
+        Domain { ranges: stack }
+    }
+
+    pub fn union(&self, domain: &Domain) -> Domain
+    {
+        let mut stack = self
+            .ranges
+            .iter()
+            .copied()
+            .chain(domain.ranges.iter().copied())
+            .collect::<Vec<DomainRange>>();
+
+        stack.sort_by(|a, b| b.start.cmp(&a.start));
+        let mut ranges = vec![];
+
+        while !stack.is_empty()
+        {
+            if stack.len() >= 2
+            {
+                let (a, b) = (stack.pop().unwrap(), stack.pop().unwrap());
+                match a.union(&b)
+                {
+                    crate::domain::UnionResult::Single(x) => stack.push(x),
+                    crate::domain::UnionResult::Union(x, y) =>
+                    {
+                        ranges.push(x);
+                        stack.push(y);
+                    }
+                }
+            }
+            else if stack.len() == 1
+            {
+                ranges.push(stack.pop().unwrap());
+            }
+        }
+
+        Domain { ranges }
+    }
+}
diff --git a/doz/src/domain/simple_range.rs b/doz/src/domain/range_ops.rs
similarity index 57%
rename from doz/src/domain/simple_range.rs
rename to doz/src/domain/range_ops.rs
index e4190ce..d8cf4fc 100644
--- a/doz/src/domain/simple_range.rs
+++ b/doz/src/domain/range_ops.rs
@@ -1,54 +1,51 @@
-use std::ops::Range;
-use std::ops::RangeFrom;
-use std::ops::RangeFull;
-use std::ops::RangeTo;
+// Module for computing intersection of domains
 
+use crate::domain::DomainRange;
 use crate::domain::HigherBound;
 use crate::domain::LowerBound;
-use crate::domain::SimpleRange;
 use crate::domain::UnionResult;
 
-impl SimpleRange
+impl DomainRange
 {
-    pub fn union(&self, range: &SimpleRange) -> UnionResult<SimpleRange>
+    pub fn union(&self, range: &DomainRange) -> UnionResult<DomainRange>
     {
         let (a, b) = (self.min_by_start(range), self.max_by_start(range));
         match (a.end, b.start)
         {
             (HigherBound::Infinity, LowerBound::Infinity) =>
             {
-                UnionResult::Single(SimpleRange::from(..))
+                UnionResult::Single(DomainRange::from(..))
             }
-            (HigherBound::Infinity, LowerBound::Bounded(_)) => UnionResult::Single(SimpleRange {
+            (HigherBound::Infinity, LowerBound::Bounded(_)) => UnionResult::Single(DomainRange {
                 start: a.start,
                 end: HigherBound::Infinity,
             }),
-            (HigherBound::Bounded(_), LowerBound::Infinity) => UnionResult::Single(SimpleRange {
+            (HigherBound::Bounded(_), LowerBound::Infinity) => UnionResult::Single(DomainRange {
                 start: LowerBound::Infinity,
                 end: b.end,
             }),
             (HigherBound::Bounded(c), LowerBound::Bounded(d)) if c < d => UnionResult::Union(a, b),
-            (HigherBound::Bounded(_), LowerBound::Bounded(_)) => UnionResult::Single(SimpleRange {
+            (HigherBound::Bounded(_), LowerBound::Bounded(_)) => UnionResult::Single(DomainRange {
                 start: a.start,
                 end: b.end,
             }),
         }
     }
 
-    pub fn intersection(&self, range: &SimpleRange) -> Option<SimpleRange>
+    pub fn intersection(&self, range: &DomainRange) -> Option<DomainRange>
     {
         let (a, b) = (self.min_by_start(range), self.max_by_start(range));
         match (a.end, b.start)
         {
-            (HigherBound::Infinity, LowerBound::Infinity) => Some(SimpleRange::from(..)),
-            (HigherBound::Infinity, LowerBound::Bounded(a)) => Some(SimpleRange::from(a..)),
-            (HigherBound::Bounded(a), LowerBound::Infinity) => Some(SimpleRange::from(..a)),
+            (HigherBound::Infinity, LowerBound::Infinity) => Some(DomainRange::from(..)),
+            (HigherBound::Infinity, LowerBound::Bounded(a)) => Some(DomainRange::from(a..)),
+            (HigherBound::Bounded(a), LowerBound::Infinity) => Some(DomainRange::from(..a)),
             (HigherBound::Bounded(a), LowerBound::Bounded(b)) if a <= b => None,
-            (HigherBound::Bounded(a), LowerBound::Bounded(b)) => Some(SimpleRange::from(a..b)),
+            (HigherBound::Bounded(a), LowerBound::Bounded(b)) => Some(DomainRange::from(a..b)),
         }
     }
 
-    pub fn without(&self, range: &SimpleRange) -> SimpleRange
+    pub fn without(&self, range: &DomainRange) -> DomainRange
     {
         match self.intersection(range)
         {
@@ -61,7 +58,7 @@ impl SimpleRange
         }
     }
 
-    pub fn symetrical_difference(&self, range: &SimpleRange) -> Option<UnionResult<SimpleRange>>
+    pub fn symetrical_difference(&self, range: &DomainRange) -> Option<UnionResult<DomainRange>>
     {
         match self.intersection(range)
         {
@@ -73,7 +70,25 @@ impl SimpleRange
         }
     }
 
-    pub fn min_by_start(&self, range: &SimpleRange) -> SimpleRange
+    pub fn disjoint(&self, range: &DomainRange) -> bool
+    {
+        self.intersection(range).is_none()
+    }
+
+    pub fn included_in(&self, range: &DomainRange) -> bool
+    {
+        if let UnionResult::Single(x) = self.union(range)
+            && x == *range
+        {
+            true
+        }
+        else
+        {
+            false
+        }
+    }
+
+    pub fn min_by_start(&self, range: &DomainRange) -> DomainRange
     {
         if self.start < range.start
         {
@@ -85,7 +100,7 @@ impl SimpleRange
         }
     }
 
-    pub fn max_by_start(&self, range: &SimpleRange) -> SimpleRange
+    pub fn max_by_start(&self, range: &DomainRange) -> DomainRange
     {
         if self.start < range.start
         {
@@ -97,57 +112,13 @@ impl SimpleRange
         }
     }
 
-    pub fn min_by_end(&self, range: &SimpleRange) -> SimpleRange
+    pub fn min_by_end(&self, range: &DomainRange) -> DomainRange
     {
         if self.end < range.end { *self } else { *range }
     }
 
-    pub fn max_by_end(&self, range: &SimpleRange) -> SimpleRange
+    pub fn max_by_end(&self, range: &DomainRange) -> DomainRange
     {
         if self.end < range.end { *range } else { *self }
     }
 }
-
-impl From<Range<i64>> for SimpleRange
-{
-    fn from(value: Range<i64>) -> Self
-    {
-        SimpleRange {
-            start: LowerBound::Bounded(value.start),
-            end: HigherBound::Bounded(value.end),
-        }
-    }
-}
-
-impl From<RangeTo<i64>> for SimpleRange
-{
-    fn from(value: RangeTo<i64>) -> Self
-    {
-        SimpleRange {
-            start: LowerBound::Infinity,
-            end: HigherBound::Bounded(value.end),
-        }
-    }
-}
-
-impl From<RangeFrom<i64>> for SimpleRange
-{
-    fn from(value: RangeFrom<i64>) -> Self
-    {
-        SimpleRange {
-            start: LowerBound::Bounded(value.start),
-            end: HigherBound::Infinity,
-        }
-    }
-}
-
-impl From<RangeFull> for SimpleRange
-{
-    fn from(_: RangeFull) -> Self
-    {
-        SimpleRange {
-            start: LowerBound::Infinity,
-            end: HigherBound::Infinity,
-        }
-    }
-}
diff --git a/doz/src/domain/union.rs b/doz/src/domain/union.rs
deleted file mode 100644
index a8db2f3..0000000
--- a/doz/src/domain/union.rs
+++ /dev/null
@@ -1,16 +0,0 @@
-// Module for computing intersection of domains
-
-use crate::domain::Domain;
-use crate::domain::DomainRange;
-
-impl DomainRange
-{
-    pub fn union(&self, domain: &DomainRange) -> Domain
-    {
-        if let Some(simple_a) = self.is_simple()
-            && let Some(simple_b) = self.is_simple()
-        {
-            simple_a.union(&simple_b)
-        }
-    }
-}
diff --git a/doz/src/lib.rs b/doz/src/lib.rs
index d7abca1..8871d95 100644
--- a/doz/src/lib.rs
+++ b/doz/src/lib.rs
@@ -1 +1,2 @@
+pub mod constraint;
 pub mod domain;
diff --git a/doz/src/main.rs b/doz/src/main.rs
index 487e411..db3758c 100644
--- a/doz/src/main.rs
+++ b/doz/src/main.rs
@@ -1,5 +1,7 @@
+use doz::constraint::Indexical;
 use doz::domain::Domain;
 use doz::domain::DomainRange;
+use doz::indexical;
 
 fn main()
 {
@@ -7,10 +9,13 @@ fn main()
         ranges: vec![DomainRange {
             start: doz::domain::LowerBound::Infinity,
             end: doz::domain::HigherBound::Infinity,
-            modulo: 2,
-            congruent: 0,
         }],
     };
 
+    //let k = Indexical::new([Box::new(|a, b, c| a), Box::new(|a, b, c| b)]);
+    //
+
+    let k = indexical![|[a, _b]| { a }, |[_a, b]| { b }];
+
     println!("{}", even);
 }