diff --git a/src/lsystem/engine/Rewrite.java b/src/lsystem/engine/Rewrite.java
new file mode 100644
index 0000000..bb2842b
--- /dev/null
+++ b/src/lsystem/engine/Rewrite.java
@@ -0,0 +1,31 @@
+package lsystem.engine;
+
+import lsystem.utils.Pair;
+
+import java.util.HashMap;
+import java.util.List;
+
+public class Rewrite {
+
+    private final String axiom;
+    private final List<Pair<String, String >> rules;
+    private final int recurrences;
+
+    public Rewrite(String axiom, List<Pair<String, String>> rules, int recurrences) {
+        this.axiom = axiom;
+        this.rules = rules;
+        this.recurrences = recurrences;
+    }
+
+    public String rewrite() {
+        String rewritted = axiom;
+        for(int i = 0; i < recurrences; ++i) {
+            for(int j = 0; j < rules.size(); ++j){
+                Pair<String, String> pair = rules.get(j);
+                rewritted = rewritted.replace(pair.getLeft(), pair.getRight());
+            }
+        }
+        return rewritted;
+    }
+
+}
diff --git a/src/lsystem/utils/Pair.java b/src/lsystem/utils/Pair.java
new file mode 100644
index 0000000..d2cfb18
--- /dev/null
+++ b/src/lsystem/utils/Pair.java
@@ -0,0 +1,40 @@
+package lsystem.utils;
+
+public class Pair<U, K> {
+
+    private final U left;
+    private final K right;
+
+    public Pair(U left, K right) {
+        this.left = left;
+        this.right = right;
+    }
+
+    public U getLeft() {
+        return left;
+    }
+
+    public K getRight() {
+        return right;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj == null) {
+            return false;
+        }
+        if (getClass() != obj.getClass()) {
+            return false;
+        }
+        final Pair<?, ?> other = (Pair<?, ?>) obj;
+        return this.left.equals(other.getLeft()) && this.left.equals(other.getRight());
+    }
+
+    @Override
+    public int hashCode() {
+        return 31 + left.hashCode() * right.hashCode();
+    }
+}