diff --git a/app/src/main/java/sudoku/Cell.java b/app/src/main/java/sudoku/Cell.java
index c7088a4..336dcfc 100644
--- a/app/src/main/java/sudoku/Cell.java
+++ b/app/src/main/java/sudoku/Cell.java
@@ -3,11 +3,11 @@ package sudoku;
 public abstract class Cell {
 
 	protected static int NOSYMBOLE = -1;
-	protected int symboleIndex;
+	protected int symbolIndex;
 	protected Block block = null;
 
-	public Cell(int symboleIndex) {
-		this.symboleIndex = symboleIndex;
+	public Cell(int symbolIndex) {
+		this.symbolIndex = symbolIndex;
 	}
 
 	/**
@@ -17,8 +17,8 @@ public abstract class Cell {
 		this(NOSYMBOLE);
 	}
 
-	public int getSymboleIndex() {
-		return symboleIndex;
+	public int getSymbolIndex() {
+		return symbolIndex;
 	}
 
 	public Block getBlock() {
@@ -33,7 +33,7 @@ public abstract class Cell {
 	@Override
 	public boolean equals(Object obj) {
 		if (obj instanceof Cell otherCell)
-			return otherCell.getSymboleIndex() == this.getSymboleIndex();
+			return otherCell.getSymbolIndex() == this.getSymbolIndex();
 		return false;
 	}
 }
diff --git a/app/src/main/java/sudoku/MutableCell.java b/app/src/main/java/sudoku/MutableCell.java
index b90d55d..7994627 100644
--- a/app/src/main/java/sudoku/MutableCell.java
+++ b/app/src/main/java/sudoku/MutableCell.java
@@ -5,38 +5,38 @@ import java.util.List;
 
 public class MutableCell extends Cell{
 
-	private final List<Integer> hintsSymbolIndex;
+	private final List<Integer> possibleSymbols;
 
 	public MutableCell() {
 		super();
-		this.hintsSymbolIndex = new ArrayList<>();
+		this.possibleSymbols = new ArrayList<>();
 	}
 
-	public MutableCell(int symboleIndex) {
-		super(symboleIndex);
-		this.hintsSymbolIndex = new ArrayList<>();
+	public MutableCell(int symbolIndex) {
+		super(symbolIndex);
+		this.possibleSymbols = new ArrayList<>();
 	}
 
-	public void setSymboleIndex(int symboleIndex) {
-		this.symboleIndex = symboleIndex;
+	public void setSymbolIndex(int symbolIndex) {
+		this.symbolIndex = symbolIndex;
 	}
 
 	/**
-	 * Remove the current symboleIndex and returns it
-	 * @return integer symboleIndex cleared
+	 * Remove the current symbolIndex and returns it
+	 * @return integer symbolIndex cleared
 	 */
-	public int clear() {
-		int i = this.symboleIndex;
-		setSymboleIndex(NOSYMBOLE);
+	public int clearCurrentSymbol() {
+		int i = this.symbolIndex;
+		setSymbolIndex(NOSYMBOLE);
 		return i;
 	}
 
-	public void removeHint(int indexSymbol) {
-		hintsSymbolIndex.remove(indexSymbol);
+	public void removeSymbolFromPossibilities(int indexSymbol) {
+		possibleSymbols.remove(indexSymbol);
 	}
 
-	public List<Integer> getHints() {
-		return this.hintsSymbolIndex;
+	public List<Integer> getPossibleSymbols() {
+		return this.possibleSymbols;
 	}
 
 }
diff --git a/app/src/main/java/sudoku/Sudoku.java b/app/src/main/java/sudoku/Sudoku.java
index 3b60963..3e20761 100644
--- a/app/src/main/java/sudoku/Sudoku.java
+++ b/app/src/main/java/sudoku/Sudoku.java
@@ -14,10 +14,12 @@ public class Sudoku {
 
 	private final List<Block> blocks;
 	private final List<Cell> cells;
+	private final List<IConstraint> constraints;
 
-	public Sudoku(List<Cell> cells, List<Block> blocks) {
+	public Sudoku(List<Cell> cells, List<Block> blocks, List<IConstraint> constraints) {
 		this.cells = cells;
 		this.blocks = blocks;
+		this.constraints = new ArrayList<>(constraints);
 	}
 
 	public Cell getCell(int x, int y) {
@@ -30,6 +32,10 @@ public class Sudoku {
 		return this.cells.get(i);
 	}
 
+	public List<IConstraint> getConstraints() {
+		return constraints;
+	}
+
 	public int getSize() {
 		return this.blocks.size();
 	}
diff --git a/app/src/main/java/sudoku/SudokuFactory.java b/app/src/main/java/sudoku/SudokuFactory.java
index dde6f27..6dfed0f 100644
--- a/app/src/main/java/sudoku/SudokuFactory.java
+++ b/app/src/main/java/sudoku/SudokuFactory.java
@@ -1,5 +1,10 @@
 package sudoku;
 
+import sudoku.constraint.BlockConstraint;
+import sudoku.constraint.ColumnConstraint;
+import sudoku.constraint.IConstraint;
+import sudoku.constraint.LineConstraint;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -37,10 +42,14 @@ public class SudokuFactory {
 		int symbolCount = width * height;
 		List<Cell> cases = initCells(symbolCount);
 		List<Block> blocs = initRectangleBlocs(cases, width, height);
-		Sudoku s = new Sudoku(cases, blocs);
-		List<Sudoku> ss = new ArrayList<>();
-		ss.add(s);
-		return new MultiDoku(ss);
+		List<IConstraint> constraints = new ArrayList<>();
+		constraints.add(new ColumnConstraint());
+		constraints.add(new LineConstraint());
+		constraints.add(new BlockConstraint());
+		Sudoku s = new Sudoku(cases, blocs, constraints);
+		List<Sudoku> subSudoku = new ArrayList<>();
+		subSudoku.add(s);
+		return new MultiDoku(subSudoku);
 	}
 
 	public static MultiDoku createBasicEmptySquareSudoku(int size) {
diff --git a/app/src/main/java/sudoku/constraint/BlockConstraint.java b/app/src/main/java/sudoku/constraint/BlockConstraint.java
index 18be660..a0fe7c5 100644
--- a/app/src/main/java/sudoku/constraint/BlockConstraint.java
+++ b/app/src/main/java/sudoku/constraint/BlockConstraint.java
@@ -2,6 +2,7 @@ package sudoku.constraint;
 
 import sudoku.Block;
 import sudoku.Cell;
+import sudoku.MutableCell;
 import sudoku.Sudoku;
 
 public class BlockConstraint implements IConstraint{
@@ -9,7 +10,7 @@ public class BlockConstraint implements IConstraint{
 	@Override
 	public boolean canBePlaced(final Sudoku s, int x, int y, int newSymbolIndex) {
 		Block bloc = s.getCell(x, y).getBlock();
-		return !bloc.getCells().contains(new Cell(newSymbolIndex));
+		return !bloc.getCells().contains(new MutableCell(newSymbolIndex));
 	}
 
 }
diff --git a/app/src/main/java/sudoku/constraint/ColumnConstraint.java b/app/src/main/java/sudoku/constraint/ColumnConstraint.java
index 4c74ef2..881faab 100644
--- a/app/src/main/java/sudoku/constraint/ColumnConstraint.java
+++ b/app/src/main/java/sudoku/constraint/ColumnConstraint.java
@@ -7,7 +7,7 @@ public class ColumnConstraint implements IConstraint {
 	@Override
 	public boolean canBePlaced(final Sudoku s, int x, int y, int newSymbolIndex) {
 		for (int i = 0; i < s.getSize(); i++) {
-			if (s.getCell(x, newSymbolIndex).getSymboleIndex() == newSymbolIndex)
+			if (s.getCell(x, newSymbolIndex).getSymbolIndex() == newSymbolIndex)
 				return false;
 		}
 		return true;
diff --git a/app/src/main/java/sudoku/constraint/LineConstraint.java b/app/src/main/java/sudoku/constraint/LineConstraint.java
index 8837229..2f9a81e 100644
--- a/app/src/main/java/sudoku/constraint/LineConstraint.java
+++ b/app/src/main/java/sudoku/constraint/LineConstraint.java
@@ -7,7 +7,7 @@ public class LineConstraint implements IConstraint {
 	@Override
 	public boolean canBePlaced(final Sudoku s, int x, int y, int newSymbolIndex) {
 		for (int i = 0; i < s.getSize(); i++) {
-			if (s.getCell(newSymbolIndex, y).getSymboleIndex() == newSymbolIndex)
+			if (s.getCell(newSymbolIndex, y).getSymbolIndex() == newSymbolIndex)
 				return false;
 		}
 		return true;
diff --git a/app/src/main/java/sudoku/solver/Solver.java b/app/src/main/java/sudoku/solver/Solver.java
index a76bbc5..cc7b80c 100644
--- a/app/src/main/java/sudoku/solver/Solver.java
+++ b/app/src/main/java/sudoku/solver/Solver.java
@@ -1,17 +1,16 @@
 package sudoku.solver;
 
-import sudoku.Cell;
 import sudoku.MultiDoku;
 import sudoku.MutableCell;
-import sudoku.Sudoku;
 import sudoku.constraint.IConstraint;
 
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Random;
+import java.util.Stack;
 
 public class Solver {
-    Caretaker stack;
+    Stack<MutableCell> stack;
 
     public Solver() {
     }
@@ -26,12 +25,21 @@ public class Solver {
         while (!remainingCellsToCheck.isEmpty()) {
             int indexCurrentCell = rand.nextInt(remainingCellsToCheck.size());
             MutableCell currentCell = remainingCellsToCheck.get(indexCurrentCell);
-            if (currentCell.getHints().isEmpty()){
-                MutableCell modify = stack.undo();
-                modify.removeHint(modify.clear());
+            if (currentCell.getPossibleSymbols().isEmpty()){
+                MutableCell modify = stack.pop();
+                modify.removeSymbolFromPossibilities(modify.clearCurrentSymbol());
+            } else {
+                int symbol = currentCell.getPossibleSymbols().get(0);
+                currentCell.setSymbolIndex(symbol);
+                stack.push(currentCell);
+                //TODO check constraints integrity in sudoku
+
+
             }
 
 
+
+
             remainingCellsToCheck.remove(indexCurrentCell);
         }
         return doku;