Minor format changes

src/sage/algebras/commutative_dga.py

@@ -501,7 +501,7 @@ def cohomology(self, n):
         H_basis_raw = [H.lift(H.basis()[i]) for i in range(H.dimension())]
         A = self.domain()
         B = A.basis(n)
-        H_basis = [sum([c*b for (c, b) in zip(coeffs, B)]) for coeffs in
+        H_basis = [sum(c*b for (c, b) in zip(coeffs, B)) for coeffs in
                    H_basis_raw]
         # Put brackets around classes.
         H_basis_brackets = [CohomologyClass(b) for b in H_basis]
@@ -790,7 +790,7 @@ def cohomology(self, n, total=False):
         H_basis_raw = [H.lift(H.basis()[i]) for i in range(H.dimension())]
         A = self.domain()
         B = A.basis(n, total)
-        H_basis = [sum([c*b for (c, b) in zip(coeffs, B)]) for coeffs in H_basis_raw]
+        H_basis = [sum(c*b for (c, b) in zip(coeffs, B)) for coeffs in H_basis_raw]
         # Put brackets around classes.
         H_basis_brackets = [CohomologyClass(b) for b in H_basis]
         return CombinatorialFreeModule(A.base_ring(), H_basis_brackets)
@@ -2416,7 +2416,7 @@ def minimal_model(self, i=3, max_iterations=3):
             raise ValueError("the degree must be a positive integer")
         if max_iterations not in ZZ or max_iterations < 1:
             raise ValueError("max_iterations must be a positive integer")
-        if max_degree in self._minimalmodels.keys():
+        if max_degree in self._minimalmodels:
             return self._minimalmodels[max_degree]
         from copy import copy
 
@@ -2522,7 +2522,7 @@ def extendy(phi, degree):
             phi = extendy(phi, degnzero+1)
             self._minimalmodels[degnzero] = phi
         else:
-            degnzero = max(self._minimalmodels.keys())
+            degnzero = max(self._minimalmodels)
             phi = self._minimalmodels[degnzero]
 
         for degree in range(degnzero+1, max_degree+1):
@@ -2567,7 +2567,7 @@ def cohomology_algebra(self, max_degree=3):
         Free module generated by {[e4*e5*e7], [e4*e5*e6]} over Rational Field
         """
         cohomgens = self.cohomology_generators(max_degree)
-        if len(cohomgens) == 0:
+        if not cohomgens:
             raise ValueError("Cohomology ring has no generators")
         chgens = []
         degrees = []

src/sage/rings/polynomial/plural.pyx

@@ -2223,9 +2223,9 @@ cdef class NCPolynomial_plural(RingElement):
 
         INPUT:
 
-        - ``codomain`` - The parent where the images live
+        - ``codomain`` -- The parent where the images live
 
-        - ``im_gens`` - A list or tuple with the images of the generators of this ring.
+        - ``im_gens`` -- A list or tuple with the images of the generators of this ring.
 
         EXAMPLES::
 
@@ -2246,7 +2246,7 @@ cdef class NCPolynomial_plural(RingElement):
             return codomain.zero()
         from sage.misc.misc_c import prod
         d = self.dict()
-        return sum(prod(im_gens[i]**t[i] for i in range(len(t)))*codomain(d[t]) for t in d)
+        return sum(prod(im_gens[i]**val for i, val in enumerate(t))*codomain(d[t]) for t in d)
 
 
     cdef long _hash_c(self):