diff --git a/src/sage/algebras/shuffle_algebra.py b/src/sage/algebras/shuffle_algebra.py
index adee056035c..aea170d2295 100644
--- a/src/sage/algebras/shuffle_algebra.py
+++ b/src/sage/algebras/shuffle_algebra.py
@@ -439,7 +439,7 @@ def _element_constructor_(self, x):
         if isinstance(P, ShuffleAlgebra):
             if P is self:
                 return x
-            if not (P is self.base_ring()):
+            if P is not self.base_ring():
                 return self.element_class(self, x.monomial_coefficients())
         if isinstance(P, DualPBWBasis):
             return self(P.expansion(x))
diff --git a/src/sage/crypto/block_cipher/miniaes.py b/src/sage/crypto/block_cipher/miniaes.py
index 0a421c17e5e..cf591029d80 100644
--- a/src/sage/crypto/block_cipher/miniaes.py
+++ b/src/sage/crypto/block_cipher/miniaes.py
@@ -1642,7 +1642,7 @@ def GF_to_binary(self, G):
             return B(S)
         # G is a matrix over GF(16)
         elif isinstance(G, Matrix_dense):
-            if not (G.base_ring() is K):
+            if G.base_ring() is not K:
                 raise TypeError("input G must be an element of GF(16), a list of elements of GF(16), or a matrix over GF(16)")
             S = "".join(str(self._GF_to_bin[G[i][j]])
                         for i in range(G.nrows()) for j in range(G.ncols()))
@@ -1772,7 +1772,7 @@ def GF_to_integer(self, G):
             return [self._GF_to_int[g] for g in G]
         # G is a matrix over GF(16)
         elif isinstance(G, Matrix_dense):
-            if not (G.base_ring() is K):
+            if G.base_ring() is not K:
                 raise TypeError("input G must be an element of GF(16), a list of elements of GF(16), or a matrix over GF(16)")
             return [self._GF_to_int[G[i][j]] for i in range(G.nrows()) for j in range(G.ncols())]
         # the type of G doesn't match the supported types
diff --git a/src/sage/dynamics/arithmetic_dynamics/berkovich_ds.py b/src/sage/dynamics/arithmetic_dynamics/berkovich_ds.py
index f84ab7e94ed..9734b3767ac 100644
--- a/src/sage/dynamics/arithmetic_dynamics/berkovich_ds.py
+++ b/src/sage/dynamics/arithmetic_dynamics/berkovich_ds.py
@@ -703,7 +703,7 @@ def conjugate(self, M, adjugate=False, new_ideal=None):
         new_system = self._system.conjugate(M, adjugate=adjugate)
         system_domain = new_system.domain()
         if new_ideal is None:
-            if not system_domain.base_ring() is QQ:
+            if system_domain.base_ring() is not QQ:
                 new_ideal = system_domain.base_ring().prime_above(self.domain().ideal())
             else:
                 new_ideal = self.domain().ideal()
diff --git a/src/sage/graphs/graph.py b/src/sage/graphs/graph.py
index 4eced79fe9b..c2e2393eaef 100644
--- a/src/sage/graphs/graph.py
+++ b/src/sage/graphs/graph.py
@@ -2695,7 +2695,7 @@ def is_perfect(self, certificate=False):
             return True if not certificate else None
 
         answer = self.is_odd_hole_free(certificate=certificate)
-        if not (answer is True):
+        if answer is not True:
             return answer
 
         return self_complement.is_odd_hole_free(certificate=certificate)
diff --git a/src/sage/groups/abelian_gps/abelian_aut.py b/src/sage/groups/abelian_gps/abelian_aut.py
index 89551916589..c58eebc4b4f 100644
--- a/src/sage/groups/abelian_gps/abelian_aut.py
+++ b/src/sage/groups/abelian_gps/abelian_aut.py
@@ -404,7 +404,7 @@ def is_subgroup_of(self, G):
         """
         if not isinstance(G, AbelianGroupAutomorphismGroup_gap):
             raise ValueError("input must be an instance of AbelianGroup_gap")
-        if not self.ambient() is G.ambient():
+        if self.ambient() is not G.ambient():
             return False
         return G.gap().IsSubsemigroup(self).sage()
 
diff --git a/src/sage/groups/abelian_gps/abelian_group_gap.py b/src/sage/groups/abelian_gps/abelian_group_gap.py
index 0c0d6a5f49b..eb41bbd8320 100644
--- a/src/sage/groups/abelian_gps/abelian_group_gap.py
+++ b/src/sage/groups/abelian_gps/abelian_group_gap.py
@@ -533,7 +533,7 @@ def is_subgroup_of(self, G):
         """
         if not isinstance(G, AbelianGroup_gap):
             raise ValueError("input must be an instance of AbelianGroup_gap")
-        if not self.ambient() is G.ambient():
+        if self.ambient() is not G.ambient():
             return False
         return G.gap().IsSubsemigroup(self).sage()
 
diff --git a/src/sage/groups/affine_gps/group_element.py b/src/sage/groups/affine_gps/group_element.py
index fff5881868f..b1e3cd1e0cb 100644
--- a/src/sage/groups/affine_gps/group_element.py
+++ b/src/sage/groups/affine_gps/group_element.py
@@ -132,9 +132,9 @@ def __init__(self, parent, A, b=0, convert=True, check=True):
             # Note: the coercion framework expects that we raise TypeError for invalid input
             if not isinstance(A, Matrix):
                 raise TypeError('A must be a matrix')
-            if not (A.parent() is parent.matrix_space()):
+            if A.parent() is not parent.matrix_space():
                 raise TypeError('A must be an element of ' + str(parent.matrix_space()))
-            if not (b.parent() is parent.vector_space()):
+            if b.parent() is not parent.vector_space():
                 raise TypeError('b must be an element of ' + str(parent.vector_space()))
             parent._element_constructor_check(A, b)
         super().__init__(parent)
diff --git a/src/sage/interfaces/psage.py b/src/sage/interfaces/psage.py
index 96d4233bbeb..9fba3d1d015 100644
--- a/src/sage/interfaces/psage.py
+++ b/src/sage/interfaces/psage.py
@@ -122,7 +122,7 @@ def __del__(self):
         except OSError:
             pass
 
-        if not (self._expect is None):
+        if self._expect is not None:
             cmd = 'kill -9 %s' % self._expect.pid
             os.system(cmd)
 
diff --git a/src/sage/logic/boolformula.py b/src/sage/logic/boolformula.py
index d22c0443461..b496bb91158 100644
--- a/src/sage/logic/boolformula.py
+++ b/src/sage/logic/boolformula.py
@@ -1106,7 +1106,7 @@ def convert_opt(self, tree):
             :func:`~sage.logic.logicparser.apply_func()` in
             :mod:`~sage.logic.logicparser`.
         """
-        if not isinstance(tree[1], tuple) and not (tree[1] is None):
+        if not isinstance(tree[1], tuple) and tree[1] is not None:
             lval = ('prop', tree[1])
         else:
             lval = tree[1]
diff --git a/src/sage/misc/rest_index_of_methods.py b/src/sage/misc/rest_index_of_methods.py
index 0d1d46f63b7..e7d4ca448ff 100644
--- a/src/sage/misc/rest_index_of_methods.py
+++ b/src/sage/misc/rest_index_of_methods.py
@@ -275,7 +275,7 @@ def local_filter(f, name):
             else:
                 return not any(hasattr(s, name) for s in superclasses)
         else:
-            return inspect.isclass(root) or not (f is gen_rest_table_index)
+            return inspect.isclass(root) or f is not gen_rest_table_index
 
     def can_import(f):
         # poke it to provoke a lazy import to resolve
diff --git a/src/sage/modules/fp_graded/morphism.py b/src/sage/modules/fp_graded/morphism.py
index 890178110a6..5f3c9e461c6 100755
--- a/src/sage/modules/fp_graded/morphism.py
+++ b/src/sage/modules/fp_graded/morphism.py
@@ -1138,7 +1138,7 @@ def lift(self, f, verbose=False):
         M = f.domain()
 
         # It is an error to call this function with incompatible arguments.
-        if not f.codomain() is N:
+        if f.codomain() is not N:
             raise ValueError('the codomains of this homomorphism and the homomorphism '
                              'we are lifting over are different')
 
diff --git a/src/sage/rings/finite_rings/galois_group.py b/src/sage/rings/finite_rings/galois_group.py
index 1cdd70fcbb2..880aea93c76 100644
--- a/src/sage/rings/finite_rings/galois_group.py
+++ b/src/sage/rings/finite_rings/galois_group.py
@@ -142,7 +142,7 @@ def _element_constructor_(self, x, check=True):
             else:
                 raise RuntimeError("Automorphism was not a power of Frobenius")
         elif isinstance(x, FrobeniusEndomorphism_finite_field):
-            if check and not x.domain() is k:
+            if check and x.domain() is not k:
                 raise ValueError("Not an automorphism of the correct finite field")
             n = x.power()
         elif isinstance(x, list) and len(x) == 1 and x[0] in ZZ:
diff --git a/src/sage/rings/invariants/invariant_theory.py b/src/sage/rings/invariants/invariant_theory.py
index fb953f98813..c2e80fbe633 100644
--- a/src/sage/rings/invariants/invariant_theory.py
+++ b/src/sage/rings/invariants/invariant_theory.py
@@ -286,7 +286,7 @@ def diff(j):
             dg = g.form().derivative(x,h-j).derivative(y,j)
             return (-1)**j * binomial(h,j) * df * dg
         tv = scalar * sum([diff(j) for j in range(h+1)])
-        if not tv.parent() is R:
+        if tv.parent() is not R:
             S = tv.parent()
             x = S(x)
             y = S(y)
diff --git a/src/sage/rings/localization.py b/src/sage/rings/localization.py
index be1fc217a8d..ab6916d36c8 100644
--- a/src/sage/rings/localization.py
+++ b/src/sage/rings/localization.py
@@ -685,9 +685,9 @@ def __init__(self, base_ring, extra_units, names=None, normalize=True, category=
             sage: L = R.localization(x**2 + 1)                                          # needs sage.libs.pari
             sage: TestSuite(L).run()
         """
-        if type(extra_units) is tuple:
+        if isinstance(extra_units, tuple):
             extra_units = list(extra_units)
-        if not type(extra_units) is list:
+        elif not isinstance(extra_units, list):
             extra_units = [extra_units]
 
         from sage.rings.polynomial.laurent_polynomial_ring_base import LaurentPolynomialRing_generic
diff --git a/src/sage/rings/number_field/number_field.py b/src/sage/rings/number_field/number_field.py
index 315e31cf42f..7128d40032e 100644
--- a/src/sage/rings/number_field/number_field.py
+++ b/src/sage/rings/number_field/number_field.py
@@ -10415,7 +10415,7 @@ def hilbert_symbol_negative_at_S(self, S, b, check=True):
         from sage.groups.additive_abelian.additive_abelian_group import AdditiveAbelianGroup
 
         # input checks
-        if not type(S) is list:
+        if not isinstance(S, list):
             raise TypeError("first argument must be a list")
         if b not in self:
             raise TypeError("second argument must be an element of this field")
diff --git a/src/sage/rings/polynomial/multi_polynomial_element.py b/src/sage/rings/polynomial/multi_polynomial_element.py
index 6c4ec02c1b1..6ffe1353fc9 100644
--- a/src/sage/rings/polynomial/multi_polynomial_element.py
+++ b/src/sage/rings/polynomial/multi_polynomial_element.py
@@ -688,7 +688,7 @@ def degree(self, x=None, std_grading=False):
                 return Integer(self.element().degree(None))
             return self.weighted_degree(self.parent().term_order().weights())
         if isinstance(x, MPolynomial):
-            if not x.parent() is self.parent():
+            if x.parent() is not self.parent():
                 try:
                     x = self.parent().coerce(x)
                 except TypeError:
diff --git a/src/sage/rings/polynomial/multi_polynomial_ideal.py b/src/sage/rings/polynomial/multi_polynomial_ideal.py
index 8e358652be3..4352d9efbac 100644
--- a/src/sage/rings/polynomial/multi_polynomial_ideal.py
+++ b/src/sage/rings/polynomial/multi_polynomial_ideal.py
@@ -638,7 +638,7 @@ def _singular_(self, singular=None):
         try:
             self.ring()._singular_(singular).set_ring()
             I = self.__singular
-            if not (I.parent() is singular):
+            if I.parent() is not singular:
                 raise ValueError
             I._check_valid()
             return I
diff --git a/src/sage/rings/polynomial/polynomial_quotient_ring.py b/src/sage/rings/polynomial/polynomial_quotient_ring.py
index 027a8997067..9851c477abf 100644
--- a/src/sage/rings/polynomial/polynomial_quotient_ring.py
+++ b/src/sage/rings/polynomial/polynomial_quotient_ring.py
@@ -216,7 +216,7 @@ def create_key(self, ring, polynomial, names=None):
             raise TypeError("ring must be a polynomial ring")
         if not isinstance(polynomial, polynomial_element.Polynomial):
             raise TypeError("must be a polynomial")
-        if not polynomial.parent() is ring:
+        if polynomial.parent() is not ring:
             raise TypeError("polynomial must be in ring")
 
         c = polynomial.leading_coefficient()
diff --git a/src/sage/rings/valuation/gauss_valuation.py b/src/sage/rings/valuation/gauss_valuation.py
index ca67b25274e..0e867e0a2f5 100644
--- a/src/sage/rings/valuation/gauss_valuation.py
+++ b/src/sage/rings/valuation/gauss_valuation.py
@@ -97,7 +97,7 @@ def create_key(self, domain, v=None):
         if v is None:
             v = domain.base_ring().valuation()
 
-        if not v.domain() is domain.base_ring():
+        if v.domain() is not domain.base_ring():
             raise ValueError("the domain of v must be the base ring of domain but %r is not defined over %r but over %r" % (v, domain.base_ring(), v.domain()))
         if not v.is_discrete_valuation():
             raise ValueError("v must be a discrete valuation but %r is not" % (v,))