diff -r 7aea2c23874a sage/rings/polynomial/plural.pyx
--- a/sage/rings/polynomial/plural.pyx	Tue Jul 20 15:16:56 2010 +0200
+++ b/sage/rings/polynomial/plural.pyx	Tue Jul 20 16:22:29 2010 +0200
@@ -89,11 +89,11 @@
             sage: A1.<x,y,z> = FreeAlgebra(QQ, 3)
             sage: R1 = A1.g_algebra({y*x:x*y-z, z*x:x*z+2*x, z*y:y*z-2*y}, order=TermOrder('degrevlex', 2))
             sage: A2.<x,y,z> = FreeAlgebra(GF(5), 3)
-            sage: R2 = A1.g_algebra({y*x:x*y-z, z*x:x*z+2*x, z*y:y*z-2*y}, order=TermOrder('degrevlex', 2))
+            sage: R2 = A2.g_algebra({y*x:x*y-z, z*x:x*z+2*x, z*y:y*z-2*y}, order=TermOrder('degrevlex', 2))
             sage: A3.<x,y,z> = FreeAlgebra(GF(11), 3)
-            sage: R3 = A1.g_algebra({y*x:x*y-z, z*x:x*z+2*x, z*y:y*z-2*y}, order=TermOrder('degrevlex', 2))
+            sage: R3 = A3.g_algebra({y*x:x*y-z, z*x:x*z+2*x, z*y:y*z-2*y}, order=TermOrder('degrevlex', 2))
             sage: A4.<x,y,z> = FreeAlgebra(GF(13), 3)
-            sage: R4 = A1.g_algebra({y*x:x*y-z, z*x:x*z+2*x, z*y:y*z-2*y}, order=TermOrder('degrevlex', 2))
+            sage: R4 = A4.g_algebra({y*x:x*y-z, z*x:x*z+2*x, z*y:y*z-2*y}, order=TermOrder('degrevlex', 2))
             sage: _ = gc.collect()
             sage: foo = R1.gen(0)
             sage: del foo
@@ -149,16 +149,16 @@
     def _repr_(self):
         """
         EXAMPLE:
-            sage: from sage.rings.polynomial.plural import MPolynomialRing_plural
+            sage: from sage.rings.polynomial.plural import NCPolynomialRing_plural
             sage: from sage.matrix.constructor  import Matrix
             sage: c=Matrix(2)
             sage: c[0,1]=-1
-            sage: P = MPolynomialRing_plural(QQ, 2, 'x,y', c=c, d=Matrix(2))
+            sage: P.<x,y> = NCPolynomialRing_plural(QQ, 2, c=c, d=Matrix(2))
             sage: P # indirect doctest
-            Noncommutative Multivariate Polynomial Ring in x, y over Rational Field
-            sage: P("x")*P("y")
+            Noncommutative Multivariate Polynomial Ring in x, y over Rational Field, nc-relations: {y*x: -x*y}
+            sage: x*y
             x*y
-            sage: P("y")*P("x")
+            sage: y*x
             -x*y
         """
 #TODO: print the relations
@@ -175,11 +175,11 @@
     def relations(self, add_commutative = False):
         """
         EXAMPLE:
-            sage: from sage.rings.polynomial.plural import MPolynomialRing_plural
+            sage: from sage.rings.polynomial.plural import NCPolynomialRing_plural
             sage: from sage.matrix.constructor  import Matrix
             sage: c=Matrix(2)
             sage: c[0,1]=-1
-            sage: P = MPolynomialRing_plural(QQ, 2, 'x,y', c=c, d=Matrix(2))
+            sage: P = NCPolynomialRing_plural(QQ, 2, 'x,y', c=c, d=Matrix(2))
             sage: P # indirect doctest
             Noncommutative Multivariate Polynomial Ring in x, y over Rational Field, nc-relations: ...
         """
@@ -891,7 +891,16 @@
 
 def SCA(base_ring, names, alt_vars, order='degrevlex'):
     """
-    sage: SCA(QQ, ['x', 'y', 'z'], [0, 1], order = 'degrevlex')
+sage: from sage.rings.polynomial.plural import SCA
+sage: E = SCA(QQ, ['x', 'y', 'z'], [0, 1], order = 'degrevlex')
+sage: E # indirect doc test
+Noncommutative Multivariate Polynomial Ring in x, y, z over Rational Field, nc-relations: {y*x: -xy}
+sage: E.inject_variables()
+Defining x, y, z
+sage: y*x
+-xy
+sage: y^2
+0
     """
     n = len(names)
     alt_start = min(alt_vars)