English
For coalgebras M and N over R, the counit of the tensor product CoalgCat.of R M ⊗ CoalgCat.of R N equals the standard counit on the ordinary tensor M ⊗_R N.
Русский
Для коалгебр M и N над R копулус (коначающий элемент) тензора CoalgCat.of R M ⊗ CoalgCat.of R N совпадает с обычным коулитом на тензоре M ⊗_R N.
LaTeX
$$$\operatorname{counit} (R := R) (A := (\mathrm{CoalgCat.of R M} \otimes \mathrm{CoalgCat.of R N} : \mathrm{CoalgCat R})) = \operatorname{counit} (A := M \otimes[R] N)$$$
Lean4
theorem counit_tensorObj :
Coalgebra.counit (R := R) (A := (CoalgCat.of R M ⊗ CoalgCat.of R N : CoalgCat R)) =
Coalgebra.counit (A := M ⊗[R] N) :=
by
rw [ofComonObjCoalgebraStruct_counit]
simp [TensorProduct.counit_def, TensorProduct.AlgebraTensorModule.rid_eq_rid, ← lid_eq_rid]
rfl