src/sage/algebras/orlik_{solomon,terao}.py: No construction for subcl…

…asses of FiniteDimensionalInvariantModule

src/sage/algebras/orlik_solomon.py

@@ -576,7 +576,7 @@ class OrlikSolomonInvariantAlgebra(FiniteDimensionalInvariantModule):
     .. NOTE::
 
         The algebra structure only exists when the action on the
-        groundset yeilds an equivariant matroid, in the sense that
+        groundset yields an equivariant matroid, in the sense that
         `g \cdot I \in \mathcal{I}` for every `g \in G` and for
         every `I \in \mathcal{I}`.
     """
@@ -638,9 +638,25 @@ def action(g, m):
                                     *args, **kwargs)
 
         # To subclass FiniteDimensionalInvariant module, we also need a
-        # self._semigroup method.
+        # self._semigroup attribute.
         self._semigroup = G
 
+    def construction(self):
+        r"""
+        Return the functorial construction of ``self``.
+
+        This implementation of the method only returns ``None``.
+
+        TESTS::
+
+            sage: M = matroids.Wheel(3)
+            sage: from sage.algebras.orlik_solomon import OrlikSolomonAlgebra
+            sage: OS1 = OrlikSolomonAlgebra(QQ, M)
+            sage: OS1.construction() is None
+            True
+        """
+        return None
+
     def _basis_action(self, g, f):
         r"""
         Return the action of the group element ``g`` on the n.b.c. set ``f``

src/sage/algebras/orlik_terao.py

@@ -660,6 +660,25 @@ def action(g, m):
 
         self._semigroup = G
 
+    def construction(self):
+        r"""
+        Return the functorial construction of ``self``.
+
+        This implementation of the method only returns ``None``.
+
+        TESTS::
+
+            sage: A = matrix([[1,1,0],[-1,0,1],[0,-1,-1]])
+            sage: M = Matroid(A)
+            sage: G = SymmetricGroup(3)
+            sage: def on_groundset(g,x):
+            ....:     return g(x+1)-1
+            sage: OTG = M.orlik_terao_algebra(QQ, invariant=(G,on_groundset))
+            sage: OTG.construction() is None
+            True
+        """
+        return None
+
     def _basis_action(self, g, f):
         r"""
         Let ``f`` be an n.b.c. set so that it indexes a basis