diff --git a/js/Solver/Inclusion.js b/js/Solver/Inclusion.js
index 16e46b6..d51bcdb 100644
--- a/js/Solver/Inclusion.js
+++ b/js/Solver/Inclusion.js
@@ -1,82 +1,83 @@
 import * as CellSet from Geometry.CellSet;
 import * as Strategy from Solver.Strategy;
 import {getColumn, getRow} from Geometry.Vector;
+import Set;
 
 return {
 	find: find
 };
 
-function find(getColor, zones, lines) {
-	return Strategy.map(
-		stepOfInclusion,
-		Strategy.tryEach([
-			findInclusion(lines.rows, zones, getColor),
-			findInclusion(lines.columns, zones, getColor),
-			findInclusion(zones, lines.rows, getRow),
-			findInclusion(zones, lines.columns, getColumn)
-		])
-	);
+function find(solvingState) {
+	var inclusion = findInclusion(cellDimensionsByname(solvingState));
+	return Strategy.tryEach([
+		inclusion('rows', 'colors'),
+		inclusion('columns', 'colors'),
+		inclusion('colors', 'rows'),
+		inclusion('colors', 'columns')
+	]);
 }
 
-function findInclusion(subsets, supersets, property) {
-	return Strategy.tryEach(
-		quotient(subsets.map(getClasses(property)), sameSet)
-			.map(keepInclusion(subsets, supersets))
-	);
+function cellDimensionsByname(solvingState) {
+	return {
+		rows: {sets: solvingState.rows, property: getRow},
+		columns: {sets: solvingState.columns, property: getColumn},
+		colors: {sets: solvingState.colorZones, property: solvingState.getColor}
+	};
 }
 
-function keepInclusion(subsets, supersets) {
-	return function(set) {
+function getAll(property) {
+	return function(cellSet) {return new Set.Int(cellSet.map(property));};
+}
+
+function getSet(namedSet) {
+	return function(i) {return namedSet.sets[i];};
+}
+
+function findInclusion(cellDimensions) {
+	return function(subName, superName) {
+		var subDimension = cellDimensions[subName];
+		var superDimension = cellDimensions[superName];
+		var diff = difference(getSet(subDimension), getSet(superDimension));
+		return Strategy.map(
+			stepOfInclusion(subName, superName),
+			Strategy.tryEach(
+				group(subDimension.sets.map(getAll(superDimension.property))).map(diff)
+			)
+		);
+	}
+}
+
+function difference(getSubset, getSuperset) {
+	return function(group) {
 		return function() {
-			if(set.occurrences.length == set.specimen.length) {
-				var superset = set.specimen.map(function(i) {return supersets[i];});
-				var subset = set.specimen.map(function(i) {return subsets[i];});
-				empty = difference(superset, subset);
-				return empty.isEmpty() ? null : empty;
+			if(group.indices.length == group.value.size()) {
+				var empty = CellSet.union(group.value.map(getSuperset))
+											.difference(CellSet.union(group.indices.map(getSubset)));
+				return empty.size() > 0 ? {empty: empty, group: group}  : null;
 			}
 		};
 	};
 }
 
-function stepOfInclusion(inclusion) {
-	return {
-		reason: 'inclusion',
-		empty: difference(inclusion.superset, inclusion.subset),
+function stepOfInclusion(subName, superName) {
+	return function(diffedGroup) {
+		var step = {reason: 'inclusion', empty: diffedGroup.empty};
+		step[subName] = diffedGroup.group.indices;
+		step['in_' + superName] = diffedGroup.group.value.toList();
+		return step;
 	};
 }
 
-function quotient(elements, equivalence) {
-	var classes = [];
-	elements.forEach(function(element, i) {
-		for(var c = 0; c < classes.length; c++) {
-			if(equivalence(element, classes[c].specimen)) {
-				classes[c].occurrences.push(i);
+function group(sets) {
+	var groups = [];
+	sets.forEach(function(set, i) {
+		for(var g = 0; g < groups.length; g++) {
+			if(groups[g].value.equals(set)) {
+				groups[g].indices.push(i);
 				return;
 			}
 		}
-		classes.push({specimen: element, occurrences: [i]});
+		groups.push({value: set, indices: [i]});
 	});
-	return classes;
-}
-
-function getClasses(property) {
-	return function(cellSet) {
-		return Array.from(quotient(
-			cellSet.getAll(property), function(a, b) {return a == b;})
-				.map(function(equivClass) {return equivClass.specimen;})
-		).sort();
-	};
-}
-
-function sameSet(s0, s1) {
-	for(var i = 0; i < s0.length; i++) {
-		if(i >= s1.length || s0[i] != s1[i]) {
-			return false;
-		}
-	}
-	return true;
-}
-
-function difference(supersets, subsets) {
-	return CellSet.union(supersets).difference(CellSet.union(subsets));
+	return groups;
 }
diff --git a/js/Solver/SingleCell.js b/js/Solver/SingleCell.js
index 95e41ab..d00c870 100644
--- a/js/Solver/SingleCell.js
+++ b/js/Solver/SingleCell.js
@@ -1,14 +1,16 @@
+import * as CellSet from Geometry.CellSet;
+import getCellSets from Solver.State;
 import * as Strategy from Solver.Strategy;
-import {diagonal, plus} from Geometry.Vector;
+import {diagonal, getColumn, getRow, plus} from Geometry.Vector;
 
 return {
 	find: find
 };
 
-function find(zones, lines) {
-	var cellSets = zones.concat(lines.rows).concat(lines.columns);
+function find(solvingState) {
+	var cellSets = getCellSets(solvingState);
 	return Strategy.map(
-		stepOfCell(cellSets),
+		stepOfCell,
 		Strategy.tryEach(cellSets.map(getSingleCellIn))
 	);
 }
@@ -16,27 +18,25 @@ function find(zones, lines) {
 function getSingleCellIn(cellSet) {
 	return function() {
 		if(cellSet.size() == 1) {
-			return cellSet.getAll(function(v) {return v;})[0];
+			return cellSet.toList()[0];
 		}
 	};
 }
 
-function stepOfCell(cellSets) {
-	return function(cell) {
-		return {
-			reason: 'singleCell',
-			empty: toEmpty(cell).intersection(cellSets),
-			star: CellSet.cells([cell])
-		};
+function stepOfCell(cell) {
+	return {
+		reason: 'singleCell',
+		empty: toEmpty(cell),
+		star: new CellSet.CellSet(cell)
 	};
 }
 
 function toEmpty(cell) {
-	var around = CellSet.rectangle(plus(cell, diagonal(-1)), diagonal(2));
-	around.remove(v);
-	return CellSet.union([
-		around,
-		CellSet.row(v.getRow()),
-		CellSet.column(v.getColumn())
+	var union = CellSet.union([
+		CellSet.rectangle(plus(cell, diagonal(-1)), diagonal(3)),
+		CellSet.row(getRow(cell)),
+		CellSet.column(getColumn(cell))
 	]);
+	union.remove(cell);
+	return union;
 }
diff --git a/js/Solver/State.js b/js/Solver/State.js
new file mode 100644
index 0000000..cc65fd5
--- /dev/null
+++ b/js/Solver/State.js
@@ -0,0 +1,35 @@
+import * as CellSet from Geometry.CellSet;
+
+return {
+	getCellSets: getCellSets,
+	start: start
+};
+
+function start(coloring) {
+	var empty = Array.from({length: size});
+	return {
+		constellation: square(size),
+		getColor: asAFunction(coloring),
+		missing: CellSet.rectangle(zero(), diagonal(size)),
+		colorZones: getZones(coloring),
+		rows: empty.map(function(_, i) {return CellSet.row(i);}),
+		columns: empty.map(function(_, i) {return CellSet.column(i);})
+	};
+}
+
+function getZones(grid) {
+	var zones = Array.from({length: size});
+	iter(grid, function(color, cell) {
+		if(zones[color] == undefined) {
+			zones[color] = new CellSet.CellSet();
+		}
+		zones[color].add(cell);
+	});
+	return zones;
+}
+
+function getCellSets(solvingState) {
+	return solvingState.colorZones
+		.concat(solvingState.rows)
+		.concat(solvingState.columns);
+}