English
The finsuppLeft isomorphism applied to a general tensor t yields the rTensor with coordinates given by Finsupp.lapply.
Русский
Изоморфизм finsuppLeft, применённый к обобщённому тензору t, даёт rTensor с координатами, заданными Finsupp.lapply.
LaTeX
$$$finsuppLeft R M N ι t = rTensor N (Finsupp.lapply ι) t$$$
Lean4
theorem finsuppLeft_apply (t : (ι →₀ M) ⊗[R] N) (i : ι) : finsuppLeft R M N ι t i = rTensor N (Finsupp.lapply i) t := by
induction t with
| zero => simp
| tmul f n => simp only [finsuppLeft_apply_tmul_apply, rTensor_tmul, Finsupp.lapply_apply]
| add x y hx hy => simp [map_add, hx, hy]