File: Mathlib/Analysis/Normed/Field/InfiniteSum.lean

full_name: Summable.mul_of_nonneg
code: theorem Summable.mul_of_nonneg {f : ι → ℝ} {g : ι' → ℝ} (hf : Summable f) (hg : Summable g)
    (hf' : 0 ≤ f) (hg' : 0 ≤ g) : Summable fun x : ι × ι' => f x.1 * g x.2 
goal: Summable fun x => f x.1 * g x.2

full_name: Summable.mul_norm
code: theorem Summable.mul_norm {f : ι → R} {g : ι' → R} (hf : Summable fun x => ‖f x‖)
    (hg : Summable fun x => ‖g x‖) : Summable fun x : ι × ι' => ‖f x.1 * g x.2‖ 
goal: Summable fun x => ‖f x.1 * g x.2‖

full_name: summable_mul_of_summable_norm
code: theorem summable_mul_of_summable_norm [CompleteSpace R] {f : ι → R} {g : ι' → R}
    (hf : Summable fun x => ‖f x‖) (hg : Summable fun x => ‖g x‖) :
    Summable fun x : ι × ι' => f x.1 * g x.2 
goal: Summable fun x => f x.1 * g x.2

full_name: tsum_mul_tsum_of_summable_norm
code: /-- Product of two infinites sums indexed by arbitrary types.
    See also `tsum_mul_tsum` if `f` and `g` are *not* absolutely summable. -/
theorem tsum_mul_tsum_of_summable_norm [CompleteSpace R] {f : ι → R} {g : ι' → R}
    (hf : Summable fun x => ‖f x‖) (hg : Summable fun x => ‖g x‖) :
    ((∑' x, f x) * ∑' y, g y) = ∑' z : ι × ι', f z.1 * g z.2 
goal: (∑' (x : ι), f x) * ∑' (y : ι'), g y = ∑' (z : ι × ι'), f z.1 * g z.2

full_name: summable_norm_sum_mul_antidiagonal_of_summable_norm
code: theorem summable_norm_sum_mul_antidiagonal_of_summable_norm {f g : ℕ → R}
    (hf : Summable fun x => ‖f x‖) (hg : Summable fun x => ‖g x‖) :
    Summable fun n => ‖∑ kl ∈ antidiagonal n, f kl.1 * g kl.2‖ 
goal: Summable fun n => ‖∑ kl ∈ Finset.antidiagonal n, f kl.1 * g kl.2‖

full_name: tsum_mul_tsum_eq_tsum_sum_antidiagonal_of_summable_norm
code: /-- The Cauchy product formula for the product of two infinite sums indexed by `ℕ`,
    expressed by summing on `Finset.antidiagonal`.
    See also `tsum_mul_tsum_eq_tsum_sum_antidiagonal` if `f` and `g` are
    *not* absolutely summable. -/
theorem tsum_mul_tsum_eq_tsum_sum_antidiagonal_of_summable_norm [CompleteSpace R] {f g : ℕ → R}
    (hf : Summable fun x => ‖f x‖) (hg : Summable fun x => ‖g x‖) :
    ((∑' n, f n) * ∑' n, g n) = ∑' n, ∑ kl ∈ antidiagonal n, f kl.1 * g kl.2 
goal: (∑' (n : ℕ), f n) * ∑' (n : ℕ), g n = ∑' (n : ℕ), ∑ kl ∈ Finset.antidiagonal n, f kl.1 * g kl.2

full_name: summable_norm_sum_mul_range_of_summable_norm
code: theorem summable_norm_sum_mul_range_of_summable_norm {f g : ℕ → R} (hf : Summable fun x => ‖f x‖)
    (hg : Summable fun x => ‖g x‖) : Summable fun n => ‖∑ k ∈ range (n + 1), f k * g (n - k)‖ 
goal: Summable fun n => ‖∑ k ∈ Finset.range (n + 1), f k * g (n - k)‖

full_name: tsum_mul_tsum_eq_tsum_sum_range_of_summable_norm
code: /-- The Cauchy product formula for the product of two infinite sums indexed by `ℕ`,
    expressed by summing on `Finset.range`.
    See also `tsum_mul_tsum_eq_tsum_sum_range` if `f` and `g` are
    *not* absolutely summable. -/
theorem tsum_mul_tsum_eq_tsum_sum_range_of_summable_norm [CompleteSpace R] {f g : ℕ → R}
    (hf : Summable fun x => ‖f x‖) (hg : Summable fun x => ‖g x‖) :
    ((∑' n, f n) * ∑' n, g n) = ∑' n, ∑ k ∈ range (n + 1), f k * g (n - k) 
goal: (∑' (n : ℕ), f n) * ∑' (n : ℕ), g n = ∑' (n : ℕ), ∑ k ∈ Finset.range (n + 1), f k * g (n - k)