From: Michael Orlitzky <michael@orlitzky.com>
Date: Thu, 25 Feb 2021 23:25:18 +0000 (-0500)
Subject: Revert "eja: drop custom _is_commutative() in favor of is_commutative()."
X-Git-Url: http://gitweb.michael.orlitzky.com/?p=sage.d.git;a=commitdiff_plain;h=47671d4a72c9eaed822c066f05a26f63c7301526

Revert "eja: drop custom _is_commutative() in favor of is_commutative()."

This reverts commit fe4405d4c4e5eec48f1924fc75e6aedd08f5c938. Now that
all EJAs are commutative, we need the custom method that actually
checks it rather than the category method that always returns True.
---

diff --git a/mjo/eja/eja_algebra.py b/mjo/eja/eja_algebra.py
index e79b0e8..af7d059 100644
--- a/mjo/eja/eja_algebra.py
+++ b/mjo/eja/eja_algebra.py
@@ -423,6 +423,18 @@ class FiniteDimensionalEJA(CombinatorialFreeModule):
         """
         return "Associative" in self.category().axioms()
 
+    def _is_commutative(self):
+        r"""
+        Whether or not this algebra's multiplication table is commutative.
+
+        This method should of course always return ``True``, unless
+        this algebra was constructed with ``check_axioms=False`` and
+        passed an invalid multiplication table.
+        """
+        return all( self.product_on_basis(i,j) == self.product_on_basis(i,j)
+                    for i in range(self.dimension())
+                    for j in range(self.dimension()) )
+
     def _is_jordanian(self):
         r"""
         Whether or not this algebra's multiplication table respects the
@@ -430,7 +442,7 @@ class FiniteDimensionalEJA(CombinatorialFreeModule):
 
         We only check one arrangement of `x` and `y`, so for a
         ``True`` result to be truly true, you should also check
-        :meth:`is_commutative`. This method should of course always
+        :meth:`_is_commutative`. This method should of course always
         return ``True``, unless this algebra was constructed with
         ``check_axioms=False`` and passed an invalid multiplication table.
         """