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Mathlib.Data.NNRat.BigOperators

Casting lemmas for non-negative rational numbers involving sums and products #

theorem NNRat.cast_sum {α : Type u_1} {K : Type u_2} [DivisionSemiring K] [CharZero K] (s : Finset α) (f : α → ℚ≥0) :
↑(∑ a ∈ s, f a) = ∑ a ∈ s, ↑(f a)
theorem NNRat.cast_prod {α : Type u_1} {K : Type u_2} [Semifield K] [CharZero K] (s : Finset α) (f : α → ℚ≥0) :
↑(∏ a ∈ s, f a) = ∏ a ∈ s, ↑(f a)
theorem NNRat.toNNRat_sum_of_nonneg {α : Type u_1} {s : Finset α} {f : α → ℚ} (hf : ∀ a ∈ s, 0 ≤ f a) :
(∑ a ∈ s, f a).toNNRat = ∑ a ∈ s, (f a).toNNRat
theorem NNRat.toNNRat_prod_of_nonneg {α : Type u_1} {s : Finset α} {f : α → ℚ} (hf : ∀ a ∈ s, 0 ≤ f a) :
(∏ a ∈ s, f a).toNNRat = ∏ a ∈ s, (f a).toNNRat