matrix_algebra: fix conditional categories.

diff --git a/mjo/matrix_algebra.py b/mjo/matrix_algebra.py
index 8f75ef20bc557b631daa1c0b8a31e7fa74dc2568..a695b0b7919edfb243cd96fd2592aa2f9fa916df 100644 (file)
--- a/mjo/matrix_algebra.py
+++ b/mjo/matrix_algebra.py
@@ -183,9 +183,9 @@ class MatrixAlgebra(CombinatorialFreeModule):
         category = category.WithBasis()
 
         if "Unital" in entry_algebra.category().axioms():
-            category.Unital()
+            category = category.Unital()
         if "Associative" in entry_algebra.category().axioms():
-            category.Associative()
+            category = category.Associative()
 
         self._nrows = n