diff --git a/.idea/workspace.xml b/.idea/workspace.xml
index ab06878a..817ad8a2 100644
--- a/.idea/workspace.xml
+++ b/.idea/workspace.xml
@@ -5,8 +5,11 @@
   </component>
   <component name="ChangeListManager">
     <list default="true" id="48b609c4-0198-44a9-8f40-0a1e1f4ae31e" name="Changes" comment="first theorem implementation">
+      <change afterPath="$PROJECT_DIR$/src/punctilious/_operators_1_representations.py" afterDir="false" />
       <change beforePath="$PROJECT_DIR$/.idea/workspace.xml" beforeDir="false" afterPath="$PROJECT_DIR$/.idea/workspace.xml" afterDir="false" />
-      <change beforePath="$PROJECT_DIR$/tests/test_shared_library.py" beforeDir="false" afterPath="$PROJECT_DIR$/tests/test_shared_library.py" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/src/punctilious/__init__.py" beforeDir="false" afterPath="$PROJECT_DIR$/src/punctilious/__init__.py" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/src/punctilious/_formal_language.py" beforeDir="false" afterPath="$PROJECT_DIR$/src/punctilious/_formal_language.py" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/tests/test_formula.py" beforeDir="false" afterPath="$PROJECT_DIR$/tests/test_formula.py" afterDir="false" />
     </list>
     <option name="SHOW_DIALOG" value="false" />
     <option name="HIGHLIGHT_CONFLICTS" value="true" />
@@ -199,7 +202,7 @@
     "Python tests.pytest for test_axiomatic_system_1.TestVariable.test_variable.executor": "Debug",
     "Python tests.pytest for test_axiomatic_system_1.test_is_extension.executor": "Run",
     "Python tests.pytest for test_fl1.TestFormalObject.test_formal_object.executor": "Run",
-    "Python tests.pytest for test_formula.TestFormula.test_formula.executor": "Run",
+    "Python tests.pytest for test_formula.TestFormula.test_formula.executor": "Debug",
     "Python tests.pytest for test_formula_notations.TestFormulaNotations.test_formula_notation.executor": "Run",
     "Python tests.pytest for test_formula_notations.TestFormulaNotations.test_formula_notations.executor": "Run",
     "Python tests.pytest for test_formula_notations.TestFormulaNotations.test_infix_notation.executor": "Run",
@@ -383,7 +386,7 @@
     "Shell Script.build_docs.sh.executor": "Run",
     "git-widget-placeholder": "master",
     "ignore.virus.scanning.warn.message": "true",
-    "last_opened_file_path": "/Users/daviddoret/PycharmProjects/punctilious/tests",
+    "last_opened_file_path": "/Users/daviddoret/PycharmProjects/punctilious/src/punctilious",
     "settings.editor.selected.configurable": "preferences.pluginManager",
     "timeTracker.activityTracker": "null",
     "timeTracker.comment": "",
@@ -447,10 +450,10 @@
   </component>
   <component name="RecentsManager">
     <key name="CopyFile.RECENT_KEYS">
+      <recent name="$PROJECT_DIR$/src/punctilious" />
       <recent name="$PROJECT_DIR$/tests" />
       <recent name="$PROJECT_DIR$/src/punctilious/data/constants" />
       <recent name="$PROJECT_DIR$/src/punctilious/data" />
-      <recent name="$PROJECT_DIR$/src/punctilious" />
       <recent name="$PROJECT_DIR$/src/punctilious/data/mappings" />
     </key>
     <key name="MoveFile.RECENT_KEYS">
@@ -461,7 +464,7 @@
       <recent name="$PROJECT_DIR$/src/punctilious/data2/mappings" />
     </key>
   </component>
-  <component name="RunManager" selected="Python tests.pytest for test_packaging.TestPackaging.test_bundling">
+  <component name="RunManager" selected="Python tests.pytest for test_formula.TestFormula.test_formula">
     <configuration name="build" type="PythonConfigurationType" factoryName="Python" nameIsGenerated="true">
       <module name="2023_05_02_PyCharmProject_Maths" />
       <option name="ENV_FILES" value="" />
@@ -668,7 +671,7 @@
       <option name="_new_targetType" value="&quot;PYTHON&quot;" />
       <method v="2" />
     </configuration>
-    <configuration name="pytest for test_identifiers.TestSlug" type="tests" factoryName="py.test" temporary="true" nameIsGenerated="true">
+    <configuration name="pytest for test_formula.TestFormula.test_formula" type="tests" factoryName="py.test" temporary="true" nameIsGenerated="true">
       <module name="2023_05_02_PyCharmProject_Maths" />
       <option name="ENV_FILES" value="" />
       <option name="INTERPRETER_OPTIONS" value="" />
@@ -681,7 +684,7 @@
       <option name="_new_keywords" value="&quot;&quot;" />
       <option name="_new_parameters" value="&quot;&quot;" />
       <option name="_new_additionalArguments" value="&quot;&quot;" />
-      <option name="_new_target" value="&quot;test_identifiers.TestSlug&quot;" />
+      <option name="_new_target" value="&quot;test_formula.TestFormula.test_formula&quot;" />
       <option name="_new_targetType" value="&quot;PYTHON&quot;" />
       <method v="2" />
     </configuration>
@@ -798,7 +801,7 @@
       <item itemvalue="Python tests.pytest for test_axiomatic_system_1.TestAreValidStatementsInTheoryWithVariables.test_are_valid_statements_in_theory_with_variables" />
       <item itemvalue="Python tests.pytest for test_minimal_logic_1.TestPL5.test_pl5_with_auto_derivation" />
       <item itemvalue="Python tests.pytest in punctilious" />
-      <item itemvalue="Python tests.pytest for test_identifiers.TestSlug" />
+      <item itemvalue="Python tests.pytest for test_formula.TestFormula.test_formula" />
       <item itemvalue="Python tests.pytest for test_identifiers.TestSlug.test_unique_identifier" />
       <item itemvalue="Python tests.pytest for test_packaging.TestPackaging.test_bundling" />
       <item itemvalue="Python tests.pytest in test_greek_alphabet_lowercase_serif_italic.py" />
@@ -809,11 +812,11 @@
     </list>
     <recent_temporary>
       <list>
-        <item itemvalue="Python tests.pytest for test_packaging.TestPackaging.test_bundling" />
+        <item itemvalue="Python tests.pytest for test_formula.TestFormula.test_formula" />
         <item itemvalue="Python tests.pytest in tests" />
+        <item itemvalue="Python tests.pytest for test_packaging.TestPackaging.test_bundling" />
         <item itemvalue="Python tests.pytest in test_greek_alphabet_lowercase_serif_italic.py" />
         <item itemvalue="Python tests.pytest for test_identifiers.TestSlug.test_unique_identifier" />
-        <item itemvalue="Python tests.pytest for test_identifiers.TestSlug" />
       </list>
     </recent_temporary>
   </component>
@@ -833,14 +836,6 @@
       <option name="presentableId" value="Default" />
       <updated>1687980987309</updated>
     </task>
-    <task id="LOCAL-01175" summary="interpretation integrated with foundations">
-      <option name="closed" value="true" />
-      <created>1733644925706</created>
-      <option name="number" value="01175" />
-      <option name="presentableId" value="LOCAL-01175" />
-      <option name="project" value="LOCAL" />
-      <updated>1733644925706</updated>
-    </task>
     <task id="LOCAL-01176" summary="interpretation integrated with foundations">
       <option name="closed" value="true" />
       <created>1733645125055</created>
@@ -1225,7 +1220,15 @@
       <option name="project" value="LOCAL" />
       <updated>1734726097638</updated>
     </task>
-    <option name="localTasksCounter" value="1224" />
+    <task id="LOCAL-01224" summary="first theorem implementation">
+      <option name="closed" value="true" />
+      <created>1734726646132</created>
+      <option name="number" value="01224" />
+      <option name="presentableId" value="LOCAL-01224" />
+      <option name="project" value="LOCAL" />
+      <updated>1734726646132</updated>
+    </task>
+    <option name="localTasksCounter" value="1225" />
     <servers>
       <YouTrack url="https://punctilious.youtrack.cloud">
         <username>random</username>
@@ -1401,6 +1404,26 @@
           <line>15</line>
           <option name="timeStamp" value="330" />
         </line-breakpoint>
+        <line-breakpoint enabled="true" suspend="THREAD" type="python-line">
+          <url>file://$PROJECT_DIR$/tests/test_formula.py</url>
+          <line>17</line>
+          <option name="timeStamp" value="331" />
+        </line-breakpoint>
+        <line-breakpoint enabled="true" suspend="THREAD" type="python-line">
+          <url>file://$PROJECT_DIR$/src/punctilious/__init__.py</url>
+          <line>43</line>
+          <option name="timeStamp" value="333" />
+        </line-breakpoint>
+        <line-breakpoint enabled="true" suspend="THREAD" type="python-line">
+          <url>file://$PROJECT_DIR$/src/punctilious/_operators_1_representations.py</url>
+          <line>13</line>
+          <option name="timeStamp" value="334" />
+        </line-breakpoint>
+        <line-breakpoint enabled="true" suspend="THREAD" type="python-line">
+          <url>file://$PROJECT_DIR$/src/punctilious/_bundling.py</url>
+          <line>272</line>
+          <option name="timeStamp" value="337" />
+        </line-breakpoint>
       </breakpoints>
       <default-breakpoints>
         <breakpoint type="python-exception">
diff --git a/src/punctilious/__init__.py b/src/punctilious/__init__.py
index 1d5b6d21..2b7a8700 100644
--- a/src/punctilious/__init__.py
+++ b/src/punctilious/__init__.py
@@ -21,6 +21,7 @@
 import _latin_alphabet_uppercase_serif_italic
 # import _latin_alphabet_lowercase_serif_roman
 import _operators_1
+import _operators_1_representations
 
 # import _propositional_logic_1
 # import _tao_analysis_1_2006
@@ -34,7 +35,10 @@
 greek_alphabet_uppercase_serif_italic = _greek_alphabet_uppercase_serif_italic.GreekAlphabetUppercaseSerifItalic()
 latin_alphabet_lowercase_serif_italic = _latin_alphabet_lowercase_serif_italic.LatinAlphabetLowercaseSerifItalic()
 latin_alphabet_uppercase_serif_italic = _latin_alphabet_uppercase_serif_italic.LatinAlphabetUppercaseSerifItalic()
+
 operators_1 = _operators_1.Operators1()
+# TODO: Resume here to assure operators are enriched with representations.
+operators_1_representations = _operators_1_representations.Operators1Representations()
 
 # tao_analysis_1_2006 = _tao_analysis_1_2006.TaoAnalysis12006()
 pass
diff --git a/src/punctilious/__pycache__/__init__.cpython-312.pyc b/src/punctilious/__pycache__/__init__.cpython-312.pyc
index 07f974df..dee4e677 100644
Binary files a/src/punctilious/__pycache__/__init__.cpython-312.pyc and b/src/punctilious/__pycache__/__init__.cpython-312.pyc differ
diff --git a/src/punctilious/__pycache__/_formal_language.cpython-312.pyc b/src/punctilious/__pycache__/_formal_language.cpython-312.pyc
index 08ad1dd3..b1cfce62 100644
Binary files a/src/punctilious/__pycache__/_formal_language.cpython-312.pyc and b/src/punctilious/__pycache__/_formal_language.cpython-312.pyc differ
diff --git a/src/punctilious/__pycache__/_operators_1_representations.cpython-312.pyc b/src/punctilious/__pycache__/_operators_1_representations.cpython-312.pyc
new file mode 100644
index 00000000..05a5b689
Binary files /dev/null and b/src/punctilious/__pycache__/_operators_1_representations.cpython-312.pyc differ
diff --git a/src/punctilious/_formal_language.py b/src/punctilious/_formal_language.py
index ac0eb7fd..6bd5ab45 100644
--- a/src/punctilious/_formal_language.py
+++ b/src/punctilious/_formal_language.py
@@ -57,7 +57,7 @@ def __repr__(self):
         return self.connector.__str__() + self.arguments.__str__()
 
     def __str__(self):
-        return self.connector.__str__() + self.arguments.__str__()
+        return self.represent()
 
     @property
     def arguments(self) -> FormulaArguments:
@@ -67,7 +67,6 @@ def arguments(self) -> FormulaArguments:
     def connector(self) -> Connector:
         return self[0]
 
-    @property
     def represent(self):
         return self.connector.rep_formula(argument=self.arguments)
 
@@ -428,9 +427,11 @@ def rep_formula(self, argument: FormulaArguments | None = None):
          - a1, a2, ..., an are the formula arguments.
         """
         if self.formula_representation is None:
-            raise ValueError(f'Connector {self.slug} has no formula representation.')
+            raise ValueError(f'Connector {self.uid} has no formula representation.')
+        connector: str = self.rep()
         argument = ensure_formula_arguments(argument)
-        variables = {'connector': self, 'argument': argument}
+        argument_representations = tuple(a.represent() for a in argument)
+        variables = {'connector': connector, 'argument': argument_representations}
         return self.formula_representation.rep(variables=variables)
 
     @property
diff --git a/src/punctilious/_operators_1_representations.py b/src/punctilious/_operators_1_representations.py
new file mode 100644
index 00000000..1837221e
--- /dev/null
+++ b/src/punctilious/_operators_1_representations.py
@@ -0,0 +1,24 @@
+import _util
+import _representation
+import _formal_language
+import _bundling
+
+
+class Operators1Representations(_bundling.YamlFileBundle):
+    """A punctilious package of well-known mathematical operators."""
+    _singleton = None
+    _singleton_initialized = None
+
+    def __init__(self):
+        if self.__class__._singleton_initialized is None:
+            path = 'data.representations'
+            resource = 'operators_1.yaml'
+            super().__init__(path=path, resource=resource)
+            self.__class__._singleton_initialized = True
+            _util.get_logger().debug(
+                f'Operators1Representations 1 singleton ({id(self)}) initialized.')
+
+    def __new__(cls, *args, **kwargs):
+        if cls._singleton is None:
+            cls._singleton = super(Operators1Representations, cls).__new__(cls)
+        return cls._singleton
diff --git a/tests/__pycache__/test_formula.cpython-312-pytest-8.3.2.pyc b/tests/__pycache__/test_formula.cpython-312-pytest-8.3.2.pyc
index 19d50fa2..cf4e12b5 100644
Binary files a/tests/__pycache__/test_formula.cpython-312-pytest-8.3.2.pyc and b/tests/__pycache__/test_formula.cpython-312-pytest-8.3.2.pyc differ
diff --git a/tests/__pycache__/test_shared_library.cpython-312-pytest-8.3.2.pyc b/tests/__pycache__/test_shared_library.cpython-312-pytest-8.3.2.pyc
index 9961a3f6..22ed9d60 100644
Binary files a/tests/__pycache__/test_shared_library.cpython-312-pytest-8.3.2.pyc and b/tests/__pycache__/test_shared_library.cpython-312-pytest-8.3.2.pyc differ
diff --git a/tests/test_formula.py b/tests/test_formula.py
index ef470236..df6d9603 100644
--- a/tests/test_formula.py
+++ b/tests/test_formula.py
@@ -11,15 +11,14 @@ def test_formula(self):
         p = create_atomic_connector('P')
         q = create_atomic_connector('Q')
         r = create_atomic_connector('R')
-        lnot = create_function('not')
-        land = create_function('and')
-        is_a_proposition = create_function('is-a-proposition')
+        land = pu.operators_1.conjunction
+        lnot = pu.operators_1.negation
 
         phi1 = pu.Formula(p)
-        assert str(phi1) == 'P()'
+        assert str(phi1) == 'P'
 
         phi2 = pu.Formula(land, (p, q,))
-        assert str(phi2) == 'and(P(), Q())'
+        assert str(phi2) == 'and(P, Q)'
 
         phi3 = pu.Formula(lnot, (p,))
         assert str(phi3) == 'not(P())'