Commit 2025-07-16 13:02 e1097802
View on Github →feat(RingTheory/TensorProduct/FG) : direct limit properties of tensor products wrt finitely generated submodules (#26717)
This PR uses the fact that a module is the directed limit of its finitely generated submodules
to establish various existence properties of finitely generated submodules wrt tensor products.
For any element u : M ⊗[R] N
, there exists a finitely generated submodule P
of M
and an element t : P ⊗[R] N
whose image in M ⊗[R] N
is equal to u
.
For t : P ⊗[R] N
and t' : P' ⊗[R] N
as above, there exists a finitely generated submodule Q
of M
containing P ⊔ P'
such that the images of t
and t'
in Q ⊗[R] N
coincide.
Similar results for base change, where M
is replaced by an R
-algebra A
, and P
, P'
, Q
by finitely generated subalgebras of A
.