sage: h = SymmetricFunctions(QQ).h()
sage: S = LazySymmetricFunctions(h)
sage: E = S(lambda n: h[n])
sage: T = LazySymmetricFunctions(tensor([h, h]))
sage: X = tensor([h[1],h[[]]])
sage: Y = tensor([h[[]],h[1]])
sage: A = T.undefined()
sage: B = T.undefined()
sage: T.define_implicitly([A, B], [A - X*E(B), B - Y*E(A)])
sage: A[:5]
[h[1] # h[],
h[1] # h[1],
h[1] # h[2] + h[1, 1] # h[1],
h[1] # h[3] + 2*h[1, 1] # h[1, 1] + h[2, 1] # h[1]]
:-)
diff --git a/src/sage/rings/lazy_series_ring.py
b/src/sage/rings/lazy_series_ring.py
index 02a477e4e0..f168435ac9 100644
--- a/src/sage/rings/lazy_series_ring.py
+++ b/src/sage/rings/lazy_series_ring.py
@@ -3147,6 +3147,7 @@ class LazyCompletionGradedAlgebra(LazySeriesRing):
from sage.misc.mrange import cartesian_product_iterator
from sage.categories.tensor import tensor
B = self._internal_poly_ring.base_ring()
+ B = B.change_ring(R)
if self._arity == 1:
return list(B.homogeneous_component_basis(n))
l = []
Thank you so much!
Martin
On Friday 23 February 2024 at 23:37:37 UTC+1 Martin R wrote:
> I just prepared a very long answer. Doing so I had to check something in
> my code. This in turn lead me to discover a bug, which might slightly
> change things. I am too tired right now to fix the bug (it might not be
> easy), so please give me a night.
>
> This might reduce the problem to nothing, but I don't know yet.
>
> I'm sorry!
>
> Martin
>
> On Friday 23 February 2024 at 21:07:19 UTC+1 Nils Bruin wrote:
>
>> On Friday 23 February 2024 at 06:44:39 UTC-8 Martin R wrote:
>>
>> Dear all!
>>
>> I badly need help to make the following work. Let M be a module over a
>> ring Q, and let R be a ring with a coercion from Q to R. Then I want to be
>> able to multiply elements in R with elements in tensor products of M.
>>
>>
>> It looks to me you should first base extend M to M_R, a module over R,
>> using the coercion map Q->R. So I don't think R acts on M. It acts on M_R.
>>
>> Do you want the coercion system to be smart enough to construct that base
>> extension for you? I'm not sure I'd expect the system to do that or even be
>> in favour of the system doing that on its own.
>>
>>
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