Zulip Chat Archive
Stream: general
Topic: tensor product notation issue
Kevin Buzzard (Aug 09 2020 at 02:30):
I was writing down a definition of Picard groups in Lean and I ran into the below notation issue. How am I supposed to be working here?
import linear_algebra.tensor_product
import ring_theory.noetherian
import algebra.category.Module.abelian
import algebra.category.Module.monoidal
--open_locale tensor_product -- comment this line out fixes something
-- and breaks something else
variables (R M N : Type) [comm_ring R] [add_comm_group M] [module R M]
[add_comm_group N] [module R N]
-- works iff locale open
theorem fg_of_pseudoinvertible :
nonempty (linear_equiv R (M ⊗[R] N) R) → submodule.fg (⊤ : submodule R M) :=
sorry
-- works iff locale not open
def pseudoinvertible (A : Module R) : Prop :=
∃ B, nonempty (A ⊗ B ≅ 𝟙_ (Module R))
Alex J. Best (Aug 09 2020 at 02:45):
In sections? Looks like the notations for tensor product of unbundled modules clashes with that for bundled modules (as a monoidal category) right so just stick to one within a section.
Alternatively opening the locale and then doing
infixr ` ⊗ `:70 := category_theory.monoidal_category.tensor_obj
infixr ` ⊗ `:70 := category_theory.monoidal_category.tensor_hom
works
Eric Wieser (Aug 09 2020 at 09:15):
Are those the same symbol or different symbols?
Last updated: Dec 20 2023 at 11:08 UTC