diff --git a/.idea/workspace.xml b/.idea/workspace.xml
index e8930803..7d83abc6 100644
--- a/.idea/workspace.xml
+++ b/.idea/workspace.xml
@@ -796,14 +796,6 @@
       <option name="presentableId" value="Default" />
       <updated>1687980987309</updated>
     </task>
-    <task id="LOCAL-01116" summary="Lark parser for the technical-1 representation-mode.">
-      <option name="closed" value="true" />
-      <created>1730929437760</created>
-      <option name="number" value="01116" />
-      <option name="presentableId" value="LOCAL-01116" />
-      <option name="project" value="LOCAL" />
-      <updated>1730929437761</updated>
-    </task>
     <task id="LOCAL-01117" summary="Lark parser for the technical-1 representation-mode.">
       <option name="closed" value="true" />
       <created>1731006968757</created>
@@ -1188,7 +1180,15 @@
       <option name="project" value="LOCAL" />
       <updated>1733568402563</updated>
     </task>
-    <option name="localTasksCounter" value="1165" />
+    <task id="LOCAL-01165" summary="interpretation">
+      <option name="closed" value="true" />
+      <created>1733568495565</created>
+      <option name="number" value="01165" />
+      <option name="presentableId" value="LOCAL-01165" />
+      <option name="project" value="LOCAL" />
+      <updated>1733568495565</updated>
+    </task>
+    <option name="localTasksCounter" value="1166" />
     <servers>
       <YouTrack url="https://punctilious.youtrack.cloud">
         <username>random</username>
diff --git a/src/punctilious/interpretation.py b/src/punctilious/interpretation.py
index c8592644..c0c62c2d 100644
--- a/src/punctilious/interpretation.py
+++ b/src/punctilious/interpretation.py
@@ -21,13 +21,18 @@
          | formula_expression INFIX_CONNECTOR formula_expression -> parse_infix_formula
          | PREFIX_CONNECTOR ATOMIC_CONNECTOR -> parse_prefix_formula
          | ATOMIC_CONNECTOR -> parse_atomic_formula
+         | "(" FUNCTION_CONNECTOR "(" function_formula_arguments ")" ")" -> parse_function_formula
+         | "(" formula_expression INFIX_CONNECTOR formula_expression ")" -> parse_infix_formula
+         | "(" PREFIX_CONNECTOR ATOMIC_CONNECTOR ")" -> parse_prefix_formula
+         | "(" ATOMIC_CONNECTOR ")" -> parse_atomic_formula     
          
-    function_formula_arguments : formula_expression ("," formula_expression)* -> parse_function_formula_arguments
+    function_formula_arguments . 20 : formula_expression ("," formula_expression)* -> parse_function_formula_arguments
+    parenthesized_formula_expression .10 : "(" formula_expression ")"
     
-    FUNCTION_CONNECTOR . 1 : "is-a-proposition" | "is-a-natural-number"
-    INFIX_CONNECTOR . 2 : "and" | "et" | "∧" | "^"
-    PREFIX_CONNECTOR . 3 : "not" | "non" | "¬" | "~"
-    ATOMIC_CONNECTOR . 4 : "P" | "Q" | "R"
+    FUNCTION_CONNECTOR . 4 : "not" | "non" | "¬" | "~" | "is-a-proposition" | "is-a-natural-number"
+    INFIX_CONNECTOR . 3 : "and" | "et" | "∧" | "^" | "or"
+    PREFIX_CONNECTOR . 2 : "not" | "non" | "¬" | "~"
+    ATOMIC_CONNECTOR . 1 : "P" | "Q" | "R"
     
     %import common.WS
     %ignore WS
@@ -100,4 +105,12 @@ def interpret_formula(input_string: str) -> Formula:
 formula = interpret_formula(input_string)
 input_string = "not P"
 formula = interpret_formula(input_string)
+input_string = "(P and Q)"
+formula = interpret_formula(input_string)
+input_string = "(P and Q) and (Q and P)"
+formula = interpret_formula(input_string)
+input_string = "not(not P)"
+formula = interpret_formula(input_string)
+input_string = "not(not (is-a-proposition(P) and Q) and (Q and P))"
+formula = interpret_formula(input_string)
 pass