For isinstance tests, import Expression from sage.structure.element

src/sage/arith/misc.py

@@ -4841,7 +4841,7 @@ def falling_factorial(x, a):
 
     - Jaap Spies (2006-03-05)
     """
-    from sage.symbolic.expression import Expression
+    from sage.structure.element import Expression
     x = py_scalar_to_element(x)
     a = py_scalar_to_element(a)
     if (isinstance(a, Integer) or
@@ -4935,7 +4935,7 @@ def rising_factorial(x, a):
 
     - Jaap Spies (2006-03-05)
     """
-    from sage.symbolic.expression import Expression
+    from sage.structure.element import Expression
     x = py_scalar_to_element(x)
     a = py_scalar_to_element(a)
     if (isinstance(a, Integer) or

src/sage/matrix/matrix0.pyx

@@ -5832,7 +5832,7 @@ cdef class Matrix(sage.structure.element.Matrix):
             [ 2*k + 2 -2*k - 1]
             [ 2*k + 1     -2*k]
         """
-        from sage.symbolic.expression import Expression
+        from sage.structure.element import Expression
 
         if not self.is_square():
             raise ArithmeticError("self must be a square matrix")

src/sage/matrix/matrix_integer_dense.pyx

@@ -963,7 +963,7 @@ cdef class Matrix_integer_dense(Matrix_dense):
                 try:
                     n = Integer(n)
                 except TypeError:
-                    from sage.symbolic.expression import Expression
+                    from sage.structure.element import Expression
                     if isinstance(n, Expression):
                         from sage.matrix.matrix2 import _matrix_power_symbolic
                         return _matrix_power_symbolic(self, n)

src/sage/numerical/optimize.py

@@ -384,7 +384,7 @@ def minimize(func, x0, gradient=None, hessian=None, algorithm="default",
         sage: minimize(rosen, [.1,.3,.4], gradient=rosen_der, algorithm="bfgs") # abs tol 1e-6
         (1.0, 1.0, 1.0)
     """
-    from sage.symbolic.expression import Expression
+    from sage.structure.element import Expression
     from sage.ext.fast_callable import fast_callable
     import numpy
     from scipy import optimize
@@ -505,7 +505,7 @@ def minimize_constrained(func,cons,x0,gradient=None,algorithm='default', **args)
         sage: minimize_constrained(f, c, [100, 300])
         (805.985..., 1005.985...)
     """
-    from sage.symbolic.expression import Expression
+    from sage.structure.element import Expression
     from sage.ext.fast_callable import fast_callable
     import numpy
     from scipy import optimize
@@ -751,7 +751,7 @@ def find_fit(data, model, initial_guess = None, parameters = None, variables = N
     if data.ndim != 2:
         raise ValueError("data has to be a two dimensional table of floating point numbers")
 
-    from sage.symbolic.expression import Expression
+    from sage.structure.element import Expression
 
     if isinstance(model, Expression):
         if variables is None:

src/sage/rings/asymptotic/asymptotic_ring.py

@@ -1684,7 +1684,7 @@ def __pow__(self, exponent, precision=None):
         else:
             return self.__pow_number__(exponent, precision=precision)
 
-        from sage.symbolic.expression import Expression
+        from sage.structure.element import Expression
         if isinstance(exponent, Expression) and exponent.is_constant():
             return self.__pow_number__(exponent, precision=precision)
 

src/sage/rings/complex_arb.pyx

@@ -650,7 +650,7 @@ class ComplexBallField(UniqueRepresentation, sage.rings.abc.ComplexBallField):
             # this is not implemented via an _acb_() method, because such a
             # conversion method would also be called by things like
             # CBF(re_expr, im_expr).
-            from sage.symbolic.expression import Expression
+            from sage.structure.element import Expression
             if isinstance(x, Expression):
                 # Parse the expression. Despite the method name, the result
                 # will be a complex ball.

src/sage/rings/finite_rings/integer_mod.pyx

@@ -380,7 +380,7 @@ cdef class IntegerMod_abstract(FiniteRingElement):
             try:
                 z = integer_ring.Z(value)
             except (TypeError, ValueError):
-                from sage.symbolic.expression import Expression
+                from sage.structure.element import Expression
                 if isinstance(value, Expression):
                     value = value.pyobject()
                 else:

src/sage/rings/polynomial/laurent_polynomial_ring.py

@@ -973,7 +973,7 @@ def _element_constructor_(self, x):
             ...
             TypeError: fraction must have unit denominator
         """
-        from sage.symbolic.expression import Expression
+        from sage.structure.element import Expression
         from sage.rings.fraction_field_element import FractionFieldElement
         if isinstance(x, Expression):
             return x.laurent_polynomial(ring=self)
@@ -1169,7 +1169,7 @@ def _element_constructor_(self, x, mon=None):
             sage: R(sum(P.gens()), (-1,-1,-1))
             y^-1*z^-1 + x^-1*z^-1 + x^-1*y^-1
         """
-        from sage.symbolic.expression import Expression
+        from sage.structure.element import Expression
 
         if mon is not None:
             return self.element_class(self, x, mon)

src/sage/sets/real_set.py

@@ -1103,7 +1103,7 @@ def __classcall__(cls, *args, **kwds):
         if kwds:
             raise TypeError(f'unless manifold keywords {manifold_keywords} are given, RealSet constructors take no keyword arguments')
 
-        from sage.symbolic.expression import Expression
+        from sage.structure.element import Expression
         if len(args) == 1 and isinstance(args[0], RealSet):
             return args[0]   # common optimization
         intervals = []