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Mathlib.Algebra.Group.Pointwise.Finset.Interval

Pointwise operations on intervals #

This should be kept in sync with Mathlib/Data/Set/Pointwise/Interval.lean.

Binary pointwise operations #

Note that the subset operations below only cover the cases with the largest possible intervals on the LHS: to conclude that Ioo a b * Ioo c d ⊆ Ioo (a * c) (c * d), you can use monotonicity of * and Finset.Ico_mul_Ioc_subset.

TODO: repeat these lemmas for the generality of mul_le_mul (which assumes nonnegativity), which the unprimed names have been reserved for

theorem Finset.Icc_mul_Icc_subset' {α : Type u_1} [Mul α] [Preorder α] [DecidableEq α] [MulLeftMono α] [MulRightMono α] [LocallyFiniteOrder α] (a b c d : α) :
Finset.Icc a b * Finset.Icc c d Finset.Icc (a * c) (b * d)
theorem Finset.Icc_add_Icc_subset {α : Type u_1} [Add α] [Preorder α] [DecidableEq α] [AddLeftMono α] [AddRightMono α] [LocallyFiniteOrder α] (a b c d : α) :
Finset.Icc a b + Finset.Icc c d Finset.Icc (a + c) (b + d)