Lemmas on infinite sums and products in topological monoids #
This file contains many simple lemmas on tsum, HasSum etc, which are placed here in order to
keep the basic file of definitions as short as possible.
Results requiring a group (rather than monoid) structure on the target should go in Group.lean.
Constant zero function has sum 0
Constant one function has product 1
A special case of Summable.map_iff_of_leftInverse for convenience
"A special case of Multipliable.map_iff_of_leftInverse for convenience"
Version of HasSum.update for AddCommMonoid rather than AddCommGroup.
Rather than showing that f.update has a specific sum in terms of HasSum,
it gives a relationship between the sums of f and f.update given that both exist.
Version of HasProd.update for CommMonoid rather than CommGroup.
Rather than showing that f.update has a specific product in terms of HasProd,
it gives a relationship between the products of f and f.update given that both exist.
Version of hasSum_ite_sub_hasSum for AddCommMonoid rather than AddCommGroup.
Rather than showing that the ite expression has a specific sum in terms of HasSum,
it gives a relationship between the sums of f and ite (n = b) 0 (f n) given that both exist.
Version of hasProd_ite_div_hasProd for CommMonoid rather than CommGroup.
Rather than showing that the ite expression has a specific product in terms of HasProd, it gives
a relationship between the products of f and ite (n = b) 0 (f n) given that both exist.
If f b = 0 for all b ∈ t, then the sum of f a with a ∈ s is the same as the
sum of f a with a ∈ s ∖ t.
If f b = 1 for all b ∈ t, then the product of f a with a ∈ s is the same as the
product of f a with a ∈ s ∖ t.
If f b = 0, then the sum of f a with a ∈ s is the same as the sum of f a
for a ∈ s ∖ {b}.
If f b = 1, then the product of f a with a ∈ s is the same as the product of f a for
a ∈ s ∖ {b}.
Version of tsum_eq_add_tsum_ite for AddCommMonoid rather than AddCommGroup.
Requires a different convergence assumption involving Function.update.
Version of tprod_eq_mul_tprod_ite for CommMonoid rather than CommGroup.
Requires a different convergence assumption involving Function.update.