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star_convex.linear_image (hs : star_convex 𝕜 x s) (f : E →ₗ[𝕜] F) : star_convex 𝕜 (f x) (s.image f)
begin intros y hy a b ha hb hab, obtain ⟨y', hy', rfl⟩ := hy, exact ⟨a • x + b • y', hs hy' ha hb hab, by rw [f.map_add, f.map_smul, f.map_smul]⟩, end
lemma
star_convex.linear_image
analysis.convex
src/analysis/convex/star.lean
[ "analysis.convex.segment" ]
[ "star_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
star_convex.is_linear_image (hs : star_convex 𝕜 x s) {f : E → F} (hf : is_linear_map 𝕜 f) : star_convex 𝕜 (f x) (f '' s)
hs.linear_image $ hf.mk' f
lemma
star_convex.is_linear_image
analysis.convex
src/analysis/convex/star.lean
[ "analysis.convex.segment" ]
[ "is_linear_map", "star_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
star_convex.linear_preimage {s : set F} (f : E →ₗ[𝕜] F) (hs : star_convex 𝕜 (f x) s) : star_convex 𝕜 x (s.preimage f)
begin intros y hy a b ha hb hab, rw [mem_preimage, f.map_add, f.map_smul, f.map_smul], exact hs hy ha hb hab, end
lemma
star_convex.linear_preimage
analysis.convex
src/analysis/convex/star.lean
[ "analysis.convex.segment" ]
[ "star_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
star_convex.is_linear_preimage {s : set F} {f : E → F} (hs : star_convex 𝕜 (f x) s) (hf : is_linear_map 𝕜 f) : star_convex 𝕜 x (preimage f s)
hs.linear_preimage $ hf.mk' f
lemma
star_convex.is_linear_preimage
analysis.convex
src/analysis/convex/star.lean
[ "analysis.convex.segment" ]
[ "is_linear_map", "star_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
star_convex.add {t : set E} (hs : star_convex 𝕜 x s) (ht : star_convex 𝕜 y t) : star_convex 𝕜 (x + y) (s + t)
by { rw ←add_image_prod, exact (hs.prod ht).is_linear_image is_linear_map.is_linear_map_add }
lemma
star_convex.add
analysis.convex
src/analysis/convex/star.lean
[ "analysis.convex.segment" ]
[ "is_linear_map.is_linear_map_add", "star_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
star_convex.add_left (hs : star_convex 𝕜 x s) (z : E) : star_convex 𝕜 (z + x) ((λ x, z + x) '' s)
begin intros y hy a b ha hb hab, obtain ⟨y', hy', rfl⟩ := hy, refine ⟨a • x + b • y', hs hy' ha hb hab, _⟩, rw [smul_add, smul_add, add_add_add_comm, ←add_smul, hab, one_smul], end
lemma
star_convex.add_left
analysis.convex
src/analysis/convex/star.lean
[ "analysis.convex.segment" ]
[ "one_smul", "smul_add", "star_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
star_convex.add_right (hs : star_convex 𝕜 x s) (z : E) : star_convex 𝕜 (x + z) ((λ x, x + z) '' s)
begin intros y hy a b ha hb hab, obtain ⟨y', hy', rfl⟩ := hy, refine ⟨a • x + b • y', hs hy' ha hb hab, _⟩, rw [smul_add, smul_add, add_add_add_comm, ←add_smul, hab, one_smul], end
lemma
star_convex.add_right
analysis.convex
src/analysis/convex/star.lean
[ "analysis.convex.segment" ]
[ "one_smul", "smul_add", "star_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
star_convex.preimage_add_right (hs : star_convex 𝕜 (z + x) s) : star_convex 𝕜 x ((λ x, z + x) ⁻¹' s)
begin intros y hy a b ha hb hab, have h := hs hy ha hb hab, rwa [smul_add, smul_add, add_add_add_comm, ←add_smul, hab, one_smul] at h, end
lemma
star_convex.preimage_add_right
analysis.convex
src/analysis/convex/star.lean
[ "analysis.convex.segment" ]
[ "one_smul", "smul_add", "star_convex" ]
The translation of a star-convex set is also star-convex.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
star_convex.preimage_add_left (hs : star_convex 𝕜 (x + z) s) : star_convex 𝕜 x ((λ x, x + z) ⁻¹' s)
begin rw add_comm at hs, simpa only [add_comm] using hs.preimage_add_right, end
lemma
star_convex.preimage_add_left
analysis.convex
src/analysis/convex/star.lean
[ "analysis.convex.segment" ]
[ "star_convex" ]
The translation of a star-convex set is also star-convex.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
star_convex.sub' {s : set (E × E)} (hs : star_convex 𝕜 (x, y) s) : star_convex 𝕜 (x - y) ((λ x : E × E, x.1 - x.2) '' s)
hs.is_linear_image is_linear_map.is_linear_map_sub
lemma
star_convex.sub'
analysis.convex
src/analysis/convex/star.lean
[ "analysis.convex.segment" ]
[ "is_linear_map.is_linear_map_sub", "star_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
star_convex.smul (hs : star_convex 𝕜 x s) (c : 𝕜) : star_convex 𝕜 (c • x) (c • s)
hs.linear_image $ linear_map.lsmul _ _ c
lemma
star_convex.smul
analysis.convex
src/analysis/convex/star.lean
[ "analysis.convex.segment" ]
[ "linear_map.lsmul", "star_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
star_convex.preimage_smul {c : 𝕜} (hs : star_convex 𝕜 (c • x) s) : star_convex 𝕜 x ((λ z, c • z) ⁻¹' s)
hs.linear_preimage (linear_map.lsmul _ _ c)
lemma
star_convex.preimage_smul
analysis.convex
src/analysis/convex/star.lean
[ "analysis.convex.segment" ]
[ "linear_map.lsmul", "star_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
star_convex.affinity (hs : star_convex 𝕜 x s) (z : E) (c : 𝕜) : star_convex 𝕜 (z + c • x) ((λ x, z + c • x) '' s)
begin have h := (hs.smul c).add_left z, rwa [←image_smul, image_image] at h, end
lemma
star_convex.affinity
analysis.convex
src/analysis/convex/star.lean
[ "analysis.convex.segment" ]
[ "star_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
star_convex_zero_iff : star_convex 𝕜 0 s ↔ ∀ ⦃x : E⦄, x ∈ s → ∀ ⦃a : 𝕜⦄, 0 ≤ a → a ≤ 1 → a • x ∈ s
begin refine forall_congr (λ x, forall_congr $ λ hx, ⟨λ h a ha₀ ha₁, _, λ h a b ha hb hab, _⟩), { simpa only [sub_add_cancel, eq_self_iff_true, forall_true_left, zero_add, smul_zero] using h (sub_nonneg_of_le ha₁) ha₀ }, { rw [smul_zero, zero_add], exact h hb (by { rw ←hab, exact le_add_of_nonneg_left h...
lemma
star_convex_zero_iff
analysis.convex
src/analysis/convex/star.lean
[ "analysis.convex.segment" ]
[ "forall_true_left", "smul_zero", "star_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
star_convex.add_smul_mem (hs : star_convex 𝕜 x s) (hy : x + y ∈ s) {t : 𝕜} (ht₀ : 0 ≤ t) (ht₁ : t ≤ 1) : x + t • y ∈ s
begin have h : x + t • y = (1 - t) • x + t • (x + y), { rw [smul_add, ←add_assoc, ←add_smul, sub_add_cancel, one_smul] }, rw h, exact hs hy (sub_nonneg_of_le ht₁) ht₀ (sub_add_cancel _ _), end
lemma
star_convex.add_smul_mem
analysis.convex
src/analysis/convex/star.lean
[ "analysis.convex.segment" ]
[ "one_smul", "smul_add", "star_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
star_convex.smul_mem (hs : star_convex 𝕜 0 s) (hx : x ∈ s) {t : 𝕜} (ht₀ : 0 ≤ t) (ht₁ : t ≤ 1) : t • x ∈ s
by simpa using hs.add_smul_mem (by simpa using hx) ht₀ ht₁
lemma
star_convex.smul_mem
analysis.convex
src/analysis/convex/star.lean
[ "analysis.convex.segment" ]
[ "star_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
star_convex.add_smul_sub_mem (hs : star_convex 𝕜 x s) (hy : y ∈ s) {t : 𝕜} (ht₀ : 0 ≤ t) (ht₁ : t ≤ 1) : x + t • (y - x) ∈ s
begin apply hs.segment_subset hy, rw segment_eq_image', exact mem_image_of_mem _ ⟨ht₀, ht₁⟩, end
lemma
star_convex.add_smul_sub_mem
analysis.convex
src/analysis/convex/star.lean
[ "analysis.convex.segment" ]
[ "segment_eq_image'", "star_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
star_convex.affine_preimage (f : E →ᵃ[𝕜] F) {s : set F} (hs : star_convex 𝕜 (f x) s) : star_convex 𝕜 x (f ⁻¹' s)
begin intros y hy a b ha hb hab, rw [mem_preimage, convex.combo_affine_apply hab], exact hs hy ha hb hab, end
lemma
star_convex.affine_preimage
analysis.convex
src/analysis/convex/star.lean
[ "analysis.convex.segment" ]
[ "convex.combo_affine_apply", "star_convex" ]
The preimage of a star-convex set under an affine map is star-convex.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
star_convex.affine_image (f : E →ᵃ[𝕜] F) {s : set E} (hs : star_convex 𝕜 x s) : star_convex 𝕜 (f x) (f '' s)
begin rintro y ⟨y', ⟨hy', hy'f⟩⟩ a b ha hb hab, refine ⟨a • x + b • y', ⟨hs hy' ha hb hab, _⟩⟩, rw [convex.combo_affine_apply hab, hy'f], end
lemma
star_convex.affine_image
analysis.convex
src/analysis/convex/star.lean
[ "analysis.convex.segment" ]
[ "convex.combo_affine_apply", "star_convex" ]
The image of a star-convex set under an affine map is star-convex.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
star_convex.neg (hs : star_convex 𝕜 x s) : star_convex 𝕜 (-x) (-s)
by { rw ←image_neg, exact hs.is_linear_image is_linear_map.is_linear_map_neg }
lemma
star_convex.neg
analysis.convex
src/analysis/convex/star.lean
[ "analysis.convex.segment" ]
[ "is_linear_map.is_linear_map_neg", "star_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
star_convex.sub (hs : star_convex 𝕜 x s) (ht : star_convex 𝕜 y t) : star_convex 𝕜 (x - y) (s - t)
by { simp_rw sub_eq_add_neg, exact hs.add ht.neg }
lemma
star_convex.sub
analysis.convex
src/analysis/convex/star.lean
[ "analysis.convex.segment" ]
[ "star_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
star_convex_iff_div : star_convex 𝕜 x s ↔ ∀ ⦃y⦄, y ∈ s → ∀ ⦃a b : 𝕜⦄, 0 ≤ a → 0 ≤ b → 0 < a + b → (a / (a + b)) • x + (b / (a + b)) • y ∈ s
⟨λ h y hy a b ha hb hab, begin apply h hy, { have ha', from mul_le_mul_of_nonneg_left ha (inv_pos.2 hab).le, rwa [mul_zero, ←div_eq_inv_mul] at ha' }, { have hb', from mul_le_mul_of_nonneg_left hb (inv_pos.2 hab).le, rwa [mul_zero, ←div_eq_inv_mul] at hb' }, { rw ←add_div, exact div_self hab.ne' } e...
lemma
star_convex_iff_div
analysis.convex
src/analysis/convex/star.lean
[ "analysis.convex.segment" ]
[ "div_one", "div_self", "mul_le_mul_of_nonneg_left", "mul_zero", "star_convex", "zero_lt_one" ]
Alternative definition of star-convexity, using division.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
star_convex.mem_smul (hs : star_convex 𝕜 0 s) (hx : x ∈ s) {t : 𝕜} (ht : 1 ≤ t) : x ∈ t • s
begin rw mem_smul_set_iff_inv_smul_mem₀ (zero_lt_one.trans_le ht).ne', exact hs.smul_mem hx (inv_nonneg.2 $ zero_le_one.trans ht) (inv_le_one ht), end
lemma
star_convex.mem_smul
analysis.convex
src/analysis/convex/star.lean
[ "analysis.convex.segment" ]
[ "inv_le_one", "star_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
set.ord_connected.star_convex [ordered_semiring 𝕜] [ordered_add_comm_monoid E] [module 𝕜 E] [ordered_smul 𝕜 E] {x : E} {s : set E} (hs : s.ord_connected) (hx : x ∈ s) (h : ∀ y ∈ s, x ≤ y ∨ y ≤ x) : star_convex 𝕜 x s
begin intros y hy a b ha hb hab, obtain hxy | hyx := h _ hy, { refine hs.out hx hy (mem_Icc.2 ⟨_, _⟩), calc x = a • x + b • x : (convex.combo_self hab _).symm ... ≤ a • x + b • y : add_le_add_left (smul_le_smul_of_nonneg hxy hb) _, calc a • x + b • y ≤ a • y + b • y : add_le_...
lemma
set.ord_connected.star_convex
analysis.convex
src/analysis/convex/star.lean
[ "analysis.convex.segment" ]
[ "convex.combo_self", "module", "ordered_add_comm_monoid", "ordered_semiring", "ordered_smul", "smul_le_smul_of_nonneg", "star_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
star_convex_iff_ord_connected [linear_ordered_field 𝕜] {x : 𝕜} {s : set 𝕜} (hx : x ∈ s) : star_convex 𝕜 x s ↔ s.ord_connected
by simp_rw [ord_connected_iff_uIcc_subset_left hx, star_convex_iff_segment_subset, segment_eq_uIcc]
lemma
star_convex_iff_ord_connected
analysis.convex
src/analysis/convex/star.lean
[ "analysis.convex.segment" ]
[ "linear_ordered_field", "segment_eq_uIcc", "star_convex", "star_convex_iff_segment_subset" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
not_disjoint_segment_convex_hull_triple {p q u v x y z : E} (hz : z ∈ segment 𝕜 x y) (hu : u ∈ segment 𝕜 x p) (hv : v ∈ segment 𝕜 y q) : ¬ disjoint (segment 𝕜 u v) (convex_hull 𝕜 {p, q, z})
begin rw not_disjoint_iff, obtain ⟨az, bz, haz, hbz, habz, rfl⟩ := hz, obtain rfl | haz' := haz.eq_or_lt, { rw zero_add at habz, rw [zero_smul, zero_add, habz, one_smul], refine ⟨v, right_mem_segment _ _ _, segment_subset_convex_hull _ _ hv⟩; simp }, obtain ⟨av, bv, hav, hbv, habv, rfl⟩ := hv, obtai...
lemma
not_disjoint_segment_convex_hull_triple
analysis.convex
src/analysis/convex/stone_separation.lean
[ "analysis.convex.join" ]
[ "convex_hull", "disjoint", "div_eq_inv_mul", "div_nonneg", "div_self", "fin.mk_bit0", "fin.mk_one", "finset", "finset.center_mass", "finset.center_mass_mem_convex_hull", "finset.univ", "list.foldr_cons", "list.foldr_nil", "list.pmap", "mul_assoc", "mul_comm", "mul_one", "mul_right_...
In a tetrahedron with vertices `x`, `y`, `p`, `q`, any segment `[u, v]` joining the opposite edges `[x, p]` and `[y, q]` passes through any triangle of vertices `p`, `q`, `z` where `z ∈ [x, y]`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
exists_convex_convex_compl_subset (hs : convex 𝕜 s) (ht : convex 𝕜 t) (hst : disjoint s t) : ∃ C : set E, convex 𝕜 C ∧ convex 𝕜 Cᶜ ∧ s ⊆ C ∧ t ⊆ Cᶜ
begin let S : set (set E) := {C | convex 𝕜 C ∧ disjoint C t}, obtain ⟨C, hC, hsC, hCmax⟩ := zorn_subset_nonempty S (λ c hcS hc ⟨t, ht⟩, ⟨⋃₀ c, ⟨hc.directed_on.convex_sUnion (λ s hs, (hcS hs).1), disjoint_sUnion_left.2 $ λ c hc, (hcS hc).2⟩, λ s, subset_sUnion_of_mem⟩) s ⟨hs, hst⟩, refine ⟨C, hC.1, conve...
lemma
exists_convex_convex_compl_subset
analysis.convex
src/analysis/convex/stone_separation.lean
[ "analysis.convex.join" ]
[ "convex", "convex_hull", "convex_hull_insert", "convex_hull_min", "convex_join_singleton_left", "disjoint", "not_disjoint_segment_convex_hull_triple", "segment", "subset_convex_hull", "zorn_subset_nonempty" ]
**Stone's Separation Theorem**
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex : Prop
s.pairwise $ λ x y, ∀ ⦃a b : 𝕜⦄, 0 < a → 0 < b → a + b = 1 → a • x + b • y ∈ interior s
def
strict_convex
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "interior" ]
A set is strictly convex if the open segment between any two distinct points lies is in its interior. This basically means "convex and not flat on the boundary".
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex_iff_open_segment_subset : strict_convex 𝕜 s ↔ s.pairwise (λ x y, open_segment 𝕜 x y ⊆ interior s)
forall₅_congr $ λ x hx y hy hxy, (open_segment_subset_iff 𝕜).symm
lemma
strict_convex_iff_open_segment_subset
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "forall₅_congr", "interior", "open_segment", "open_segment_subset_iff", "strict_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex.open_segment_subset (hs : strict_convex 𝕜 s) (hx : x ∈ s) (hy : y ∈ s) (h : x ≠ y) : open_segment 𝕜 x y ⊆ interior s
strict_convex_iff_open_segment_subset.1 hs hx hy h
lemma
strict_convex.open_segment_subset
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "interior", "open_segment", "strict_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex_empty : strict_convex 𝕜 (∅ : set E)
pairwise_empty _
lemma
strict_convex_empty
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "strict_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex_univ : strict_convex 𝕜 (univ : set E)
begin intros x hx y hy hxy a b ha hb hab, rw interior_univ, exact mem_univ _, end
lemma
strict_convex_univ
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "interior_univ", "strict_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex.eq (hs : strict_convex 𝕜 s) (hx : x ∈ s) (hy : y ∈ s) (ha : 0 < a) (hb : 0 < b) (hab : a + b = 1) (h : a • x + b • y ∉ interior s) : x = y
hs.eq hx hy $ λ H, h $ H ha hb hab
lemma
strict_convex.eq
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "interior", "strict_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex.inter {t : set E} (hs : strict_convex 𝕜 s) (ht : strict_convex 𝕜 t) : strict_convex 𝕜 (s ∩ t)
begin intros x hx y hy hxy a b ha hb hab, rw interior_inter, exact ⟨hs hx.1 hy.1 hxy ha hb hab, ht hx.2 hy.2 hxy ha hb hab⟩, end
lemma
strict_convex.inter
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "interior_inter", "strict_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
directed.strict_convex_Union {ι : Sort*} {s : ι → set E} (hdir : directed (⊆) s) (hs : ∀ ⦃i : ι⦄, strict_convex 𝕜 (s i)) : strict_convex 𝕜 (⋃ i, s i)
begin rintro x hx y hy hxy a b ha hb hab, rw mem_Union at hx hy, obtain ⟨i, hx⟩ := hx, obtain ⟨j, hy⟩ := hy, obtain ⟨k, hik, hjk⟩ := hdir i j, exact interior_mono (subset_Union s k) (hs (hik hx) (hjk hy) hxy ha hb hab), end
lemma
directed.strict_convex_Union
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "directed", "interior_mono", "strict_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
directed_on.strict_convex_sUnion {S : set (set E)} (hdir : directed_on (⊆) S) (hS : ∀ s ∈ S, strict_convex 𝕜 s) : strict_convex 𝕜 (⋃₀ S)
begin rw sUnion_eq_Union, exact (directed_on_iff_directed.1 hdir).strict_convex_Union (λ s, hS _ s.2), end
lemma
directed_on.strict_convex_sUnion
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "directed_on", "strict_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex.convex (hs : strict_convex 𝕜 s) : convex 𝕜 s
convex_iff_pairwise_pos.2 $ λ x hx y hy hxy a b ha hb hab, interior_subset $ hs hx hy hxy ha hb hab
lemma
strict_convex.convex
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "convex", "interior_subset", "strict_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
convex.strict_convex_of_open (h : is_open s) (hs : convex 𝕜 s) : strict_convex 𝕜 s
λ x hx y hy _ a b ha hb hab, h.interior_eq.symm ▸ hs hx hy ha.le hb.le hab
lemma
convex.strict_convex_of_open
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "convex", "is_open", "strict_convex" ]
An open convex set is strictly convex.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_open.strict_convex_iff (h : is_open s) : strict_convex 𝕜 s ↔ convex 𝕜 s
⟨strict_convex.convex, convex.strict_convex_of_open h⟩
lemma
is_open.strict_convex_iff
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "convex", "convex.strict_convex_of_open", "is_open", "strict_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex_singleton (c : E) : strict_convex 𝕜 ({c} : set E)
pairwise_singleton _ _
lemma
strict_convex_singleton
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "strict_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
set.subsingleton.strict_convex (hs : s.subsingleton) : strict_convex 𝕜 s
hs.pairwise _
lemma
set.subsingleton.strict_convex
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "strict_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex.linear_image [semiring 𝕝] [module 𝕝 E] [module 𝕝 F] [linear_map.compatible_smul E F 𝕜 𝕝] (hs : strict_convex 𝕜 s) (f : E →ₗ[𝕝] F) (hf : is_open_map f) : strict_convex 𝕜 (f '' s)
begin rintro _ ⟨x, hx, rfl⟩ _ ⟨y, hy, rfl⟩ hxy a b ha hb hab, refine hf.image_interior_subset _ ⟨a • x + b • y, hs hx hy (ne_of_apply_ne _ hxy) ha hb hab, _⟩, rw [map_add, f.map_smul_of_tower a, f.map_smul_of_tower b] end
lemma
strict_convex.linear_image
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "is_open_map", "linear_map.compatible_smul", "module", "ne_of_apply_ne", "semiring", "strict_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex.is_linear_image (hs : strict_convex 𝕜 s) {f : E → F} (h : is_linear_map 𝕜 f) (hf : is_open_map f) : strict_convex 𝕜 (f '' s)
hs.linear_image (h.mk' f) hf
lemma
strict_convex.is_linear_image
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "is_linear_map", "is_open_map", "strict_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex.linear_preimage {s : set F} (hs : strict_convex 𝕜 s) (f : E →ₗ[𝕜] F) (hf : continuous f) (hfinj : injective f) : strict_convex 𝕜 (s.preimage f)
begin intros x hx y hy hxy a b ha hb hab, refine preimage_interior_subset_interior_preimage hf _, rw [mem_preimage, f.map_add, f.map_smul, f.map_smul], exact hs hx hy (hfinj.ne hxy) ha hb hab, end
lemma
strict_convex.linear_preimage
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "continuous", "preimage_interior_subset_interior_preimage", "strict_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex.is_linear_preimage {s : set F} (hs : strict_convex 𝕜 s) {f : E → F} (h : is_linear_map 𝕜 f) (hf : continuous f) (hfinj : injective f) : strict_convex 𝕜 (s.preimage f)
hs.linear_preimage (h.mk' f) hf hfinj
lemma
strict_convex.is_linear_preimage
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "continuous", "is_linear_map", "strict_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
set.ord_connected.strict_convex {s : set β} (hs : ord_connected s) : strict_convex 𝕜 s
begin refine strict_convex_iff_open_segment_subset.2 (λ x hx y hy hxy, _), cases hxy.lt_or_lt with hlt hlt; [skip, rw [open_segment_symm]]; exact (open_segment_subset_Ioo hlt).trans (is_open_Ioo.subset_interior_iff.2 $ Ioo_subset_Icc_self.trans $ hs.out ‹_› ‹_›) end
lemma
set.ord_connected.strict_convex
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "open_segment_subset_Ioo", "open_segment_symm", "strict_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex_Iic (r : β) : strict_convex 𝕜 (Iic r)
ord_connected_Iic.strict_convex
lemma
strict_convex_Iic
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "strict_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex_Ici (r : β) : strict_convex 𝕜 (Ici r)
ord_connected_Ici.strict_convex
lemma
strict_convex_Ici
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "strict_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex_Iio (r : β) : strict_convex 𝕜 (Iio r)
ord_connected_Iio.strict_convex
lemma
strict_convex_Iio
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "strict_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex_Ioi (r : β) : strict_convex 𝕜 (Ioi r)
ord_connected_Ioi.strict_convex
lemma
strict_convex_Ioi
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "strict_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex_Icc (r s : β) : strict_convex 𝕜 (Icc r s)
ord_connected_Icc.strict_convex
lemma
strict_convex_Icc
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "strict_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex_Ioo (r s : β) : strict_convex 𝕜 (Ioo r s)
ord_connected_Ioo.strict_convex
lemma
strict_convex_Ioo
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "strict_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex_Ico (r s : β) : strict_convex 𝕜 (Ico r s)
ord_connected_Ico.strict_convex
lemma
strict_convex_Ico
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "strict_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex_Ioc (r s : β) : strict_convex 𝕜 (Ioc r s)
ord_connected_Ioc.strict_convex
lemma
strict_convex_Ioc
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "strict_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex_uIcc (r s : β) : strict_convex 𝕜 (uIcc r s)
strict_convex_Icc _ _
lemma
strict_convex_uIcc
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "strict_convex", "strict_convex_Icc" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex_uIoc (r s : β) : strict_convex 𝕜 (uIoc r s)
strict_convex_Ioc _ _
lemma
strict_convex_uIoc
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "strict_convex", "strict_convex_Ioc" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex.preimage_add_right (hs : strict_convex 𝕜 s) (z : E) : strict_convex 𝕜 ((λ x, z + x) ⁻¹' s)
begin intros x hx y hy hxy a b ha hb hab, refine preimage_interior_subset_interior_preimage (continuous_add_left _) _, have h := hs hx hy ((add_right_injective _).ne hxy) ha hb hab, rwa [smul_add, smul_add, add_add_add_comm, ←add_smul, hab, one_smul] at h, end
lemma
strict_convex.preimage_add_right
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "one_smul", "preimage_interior_subset_interior_preimage", "smul_add", "strict_convex" ]
The translation of a strictly convex set is also strictly convex.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex.preimage_add_left (hs : strict_convex 𝕜 s) (z : E) : strict_convex 𝕜 ((λ x, x + z) ⁻¹' s)
by simpa only [add_comm] using hs.preimage_add_right z
lemma
strict_convex.preimage_add_left
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "strict_convex" ]
The translation of a strictly convex set is also strictly convex.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex.add (hs : strict_convex 𝕜 s) (ht : strict_convex 𝕜 t) : strict_convex 𝕜 (s + t)
begin rintro _ ⟨v, w, hv, hw, rfl⟩ _ ⟨x, y, hx, hy, rfl⟩ h a b ha hb hab, rw [smul_add, smul_add, add_add_add_comm], obtain rfl | hvx := eq_or_ne v x, { refine interior_mono (add_subset_add (singleton_subset_iff.2 hv) subset.rfl) _, rw [convex.combo_self hab, singleton_add], exact (is_open_map_add_left ...
lemma
strict_convex.add
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "convex.combo_self", "eq_or_ne", "interior_mono", "ne_of_apply_ne", "smul_add", "strict_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex.add_left (hs : strict_convex 𝕜 s) (z : E) : strict_convex 𝕜 ((λ x, z + x) '' s)
by simpa only [singleton_add] using (strict_convex_singleton z).add hs
lemma
strict_convex.add_left
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "strict_convex", "strict_convex_singleton" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex.add_right (hs : strict_convex 𝕜 s) (z : E) : strict_convex 𝕜 ((λ x, x + z) '' s)
by simpa only [add_comm] using hs.add_left z
lemma
strict_convex.add_right
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "strict_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex.vadd (hs : strict_convex 𝕜 s) (x : E) : strict_convex 𝕜 (x +ᵥ s)
hs.add_left x
lemma
strict_convex.vadd
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "strict_convex" ]
The translation of a strictly convex set is also strictly convex.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex.smul (hs : strict_convex 𝕜 s) (c : 𝕝) : strict_convex 𝕜 (c • s)
begin obtain rfl | hc := eq_or_ne c 0, { exact (subsingleton_zero_smul_set _).strict_convex }, { exact hs.linear_image (linear_map.lsmul _ _ c) (is_open_map_smul₀ hc) } end
lemma
strict_convex.smul
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "eq_or_ne", "is_open_map_smul₀", "linear_map.lsmul", "strict_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex.affinity [has_continuous_add E] (hs : strict_convex 𝕜 s) (z : E) (c : 𝕝) : strict_convex 𝕜 (z +ᵥ c • s)
(hs.smul c).vadd z
lemma
strict_convex.affinity
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "has_continuous_add", "strict_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex.preimage_smul (hs : strict_convex 𝕜 s) (c : 𝕜) : strict_convex 𝕜 ((λ z, c • z) ⁻¹' s)
begin classical, obtain rfl | hc := eq_or_ne c 0, { simp_rw [zero_smul, preimage_const], split_ifs, { exact strict_convex_univ }, { exact strict_convex_empty } }, refine hs.linear_preimage (linear_map.lsmul _ _ c) _ (smul_right_injective E hc), unfold linear_map.lsmul linear_map.mk₂ linear_map.mk₂...
lemma
strict_convex.preimage_smul
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "eq_or_ne", "linear_map.lsmul", "linear_map.mk₂", "linear_map.mk₂'", "linear_map.mk₂'ₛₗ", "smul_right_injective", "strict_convex", "strict_convex_empty", "strict_convex_univ", "zero_smul" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex.eq_of_open_segment_subset_frontier [nontrivial 𝕜] [densely_ordered 𝕜] (hs : strict_convex 𝕜 s) (hx : x ∈ s) (hy : y ∈ s) (h : open_segment 𝕜 x y ⊆ frontier s) : x = y
begin obtain ⟨a, ha₀, ha₁⟩ := densely_ordered.dense (0 : 𝕜) 1 zero_lt_one, classical, by_contra hxy, exact (h ⟨a, 1 - a, ha₀, sub_pos_of_lt ha₁, add_sub_cancel'_right _ _, rfl⟩).2 (hs hx hy hxy ha₀ (sub_pos_of_lt ha₁) $ add_sub_cancel'_right _ _), end
lemma
strict_convex.eq_of_open_segment_subset_frontier
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "by_contra", "densely_ordered", "frontier", "nontrivial", "open_segment", "strict_convex", "zero_lt_one" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex.add_smul_mem (hs : strict_convex 𝕜 s) (hx : x ∈ s) (hxy : x + y ∈ s) (hy : y ≠ 0) {t : 𝕜} (ht₀ : 0 < t) (ht₁ : t < 1) : x + t • y ∈ interior s
begin have h : x + t • y = (1 - t) • x + t • (x + y), { rw [smul_add, ←add_assoc, ←add_smul, sub_add_cancel, one_smul] }, rw h, refine hs hx hxy (λ h, hy $ add_left_cancel _) (sub_pos_of_lt ht₁) ht₀ (sub_add_cancel _ _), exact x, rw [←h, add_zero], end
lemma
strict_convex.add_smul_mem
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "interior", "one_smul", "smul_add", "strict_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex.smul_mem_of_zero_mem (hs : strict_convex 𝕜 s) (zero_mem : (0 : E) ∈ s) (hx : x ∈ s) (hx₀ : x ≠ 0) {t : 𝕜} (ht₀ : 0 < t) (ht₁ : t < 1) : t • x ∈ interior s
by simpa using hs.add_smul_mem zero_mem (by simpa using hx) hx₀ ht₀ ht₁
lemma
strict_convex.smul_mem_of_zero_mem
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "interior", "strict_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex.add_smul_sub_mem (h : strict_convex 𝕜 s) (hx : x ∈ s) (hy : y ∈ s) (hxy : x ≠ y) {t : 𝕜} (ht₀ : 0 < t) (ht₁ : t < 1) : x + t • (y - x) ∈ interior s
begin apply h.open_segment_subset hx hy hxy, rw open_segment_eq_image', exact mem_image_of_mem _ ⟨ht₀, ht₁⟩, end
lemma
strict_convex.add_smul_sub_mem
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "interior", "open_segment_eq_image'", "strict_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex.affine_preimage {s : set F} (hs : strict_convex 𝕜 s) {f : E →ᵃ[𝕜] F} (hf : continuous f) (hfinj : injective f) : strict_convex 𝕜 (f ⁻¹' s)
begin intros x hx y hy hxy a b ha hb hab, refine preimage_interior_subset_interior_preimage hf _, rw [mem_preimage, convex.combo_affine_apply hab], exact hs hx hy (hfinj.ne hxy) ha hb hab, end
lemma
strict_convex.affine_preimage
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "continuous", "convex.combo_affine_apply", "preimage_interior_subset_interior_preimage", "strict_convex" ]
The preimage of a strictly convex set under an affine map is strictly convex.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex.affine_image (hs : strict_convex 𝕜 s) {f : E →ᵃ[𝕜] F} (hf : is_open_map f) : strict_convex 𝕜 (f '' s)
begin rintro _ ⟨x, hx, rfl⟩ _ ⟨y, hy, rfl⟩ hxy a b ha hb hab, exact hf.image_interior_subset _ ⟨a • x + b • y, ⟨hs hx hy (ne_of_apply_ne _ hxy) ha hb hab, convex.combo_affine_apply hab⟩⟩, end
lemma
strict_convex.affine_image
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "convex.combo_affine_apply", "is_open_map", "ne_of_apply_ne", "strict_convex" ]
The image of a strictly convex set under an affine map is strictly convex.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex.neg (hs : strict_convex 𝕜 s) : strict_convex 𝕜 (-s)
hs.is_linear_preimage is_linear_map.is_linear_map_neg continuous_id.neg neg_injective
lemma
strict_convex.neg
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "is_linear_map.is_linear_map_neg", "strict_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex.sub (hs : strict_convex 𝕜 s) (ht : strict_convex 𝕜 t) : strict_convex 𝕜 (s - t)
(sub_eq_add_neg s t).symm ▸ hs.add ht.neg
lemma
strict_convex.sub
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "strict_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex_iff_div : strict_convex 𝕜 s ↔ s.pairwise (λ x y, ∀ ⦃a b : 𝕜⦄, 0 < a → 0 < b → (a / (a + b)) • x + (b / (a + b)) • y ∈ interior s)
⟨λ h x hx y hy hxy a b ha hb, begin apply h hx hy hxy (div_pos ha $ add_pos ha hb) (div_pos hb $ add_pos ha hb), rw ←add_div, exact div_self (add_pos ha hb).ne', end, λ h x hx y hy hxy a b ha hb hab, by convert h hx hy hxy ha hb; rw [hab, div_one] ⟩
lemma
strict_convex_iff_div
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "div_one", "div_pos", "div_self", "interior", "strict_convex" ]
Alternative definition of set strict convexity, using division.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex.mem_smul_of_zero_mem (hs : strict_convex 𝕜 s) (zero_mem : (0 : E) ∈ s) (hx : x ∈ s) (hx₀ : x ≠ 0) {t : 𝕜} (ht : 1 < t) : x ∈ t • interior s
begin rw mem_smul_set_iff_inv_smul_mem₀ (zero_lt_one.trans ht).ne', exact hs.smul_mem_of_zero_mem zero_mem hx hx₀ (inv_pos.2 $ zero_lt_one.trans ht) (inv_lt_one ht), end
lemma
strict_convex.mem_smul_of_zero_mem
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "interior", "inv_lt_one", "strict_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex_iff_convex : strict_convex 𝕜 s ↔ convex 𝕜 s
⟨strict_convex.convex, λ hs, hs.ord_connected.strict_convex⟩
lemma
strict_convex_iff_convex
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "convex", "strict_convex" ]
A set in a linear ordered field is strictly convex if and only if it is convex.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex_iff_ord_connected : strict_convex 𝕜 s ↔ s.ord_connected
strict_convex_iff_convex.trans convex_iff_ord_connected
lemma
strict_convex_iff_ord_connected
analysis.convex
src/analysis/convex/strict.lean
[ "analysis.convex.basic", "topology.algebra.order.group" ]
[ "convex_iff_ord_connected", "strict_convex" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
sbtw.dist_lt_max_dist (p : P) {p₁ p₂ p₃ : P} (h : sbtw ℝ p₁ p₂ p₃) : dist p₂ p < max (dist p₁ p) (dist p₃ p)
begin have hp₁p₃ : p₁ -ᵥ p ≠ p₃ -ᵥ p, { by simpa using h.left_ne_right }, rw [sbtw, ←wbtw_vsub_const_iff p, wbtw, affine_segment_eq_segment, ←insert_endpoints_open_segment, set.mem_insert_iff, set.mem_insert_iff] at h, rcases h with ⟨h | h | h, hp₂p₁, hp₂p₃⟩, { rw vsub_left_cancel_iff at h, exact false.el...
lemma
sbtw.dist_lt_max_dist
analysis.convex
src/analysis/convex/strict_convex_between.lean
[ "analysis.convex.between", "analysis.convex.strict_convex_space" ]
[ "affine_segment_eq_segment", "dist_eq_norm_vsub", "norm_combo_lt_of_ne", "open_segment_eq_image", "sbtw", "set.mem_image", "set.mem_insert_iff", "vsub_left_cancel_iff", "wbtw" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
wbtw.dist_le_max_dist (p : P) {p₁ p₂ p₃ : P} (h : wbtw ℝ p₁ p₂ p₃) : dist p₂ p ≤ max (dist p₁ p) (dist p₃ p)
begin by_cases hp₁ : p₂ = p₁, { simp [hp₁] }, by_cases hp₃ : p₂ = p₃, { simp [hp₃] }, have hs : sbtw ℝ p₁ p₂ p₃ := ⟨h, hp₁, hp₃⟩, exact (hs.dist_lt_max_dist _).le end
lemma
wbtw.dist_le_max_dist
analysis.convex
src/analysis/convex/strict_convex_between.lean
[ "analysis.convex.between", "analysis.convex.strict_convex_space" ]
[ "sbtw", "wbtw" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
collinear.wbtw_of_dist_eq_of_dist_le {p p₁ p₂ p₃ : P} {r : ℝ} (h : collinear ℝ ({p₁, p₂, p₃} : set P)) (hp₁ : dist p₁ p = r) (hp₂ : dist p₂ p ≤ r) (hp₃ : dist p₃ p = r) (hp₁p₃ : p₁ ≠ p₃) : wbtw ℝ p₁ p₂ p₃
begin rcases h.wbtw_or_wbtw_or_wbtw with hw | hw | hw, { exact hw }, { by_cases hp₃p₂ : p₃ = p₂, { simp [hp₃p₂] }, have hs : sbtw ℝ p₂ p₃ p₁ := ⟨hw, hp₃p₂, hp₁p₃.symm⟩, have hs' := hs.dist_lt_max_dist p, rw [hp₁, hp₃, lt_max_iff, lt_self_iff_false, or_false] at hs', exact false.elim (hp₂.not_lt hs...
lemma
collinear.wbtw_of_dist_eq_of_dist_le
analysis.convex
src/analysis/convex/strict_convex_between.lean
[ "analysis.convex.between", "analysis.convex.strict_convex_space" ]
[ "collinear", "lt_max_iff", "lt_self_iff_false", "sbtw", "wbtw" ]
Given three collinear points, two (not equal) with distance `r` from `p` and one with distance at most `r` from `p`, the third point is weakly between the other two points.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
collinear.sbtw_of_dist_eq_of_dist_lt {p p₁ p₂ p₃ : P} {r : ℝ} (h : collinear ℝ ({p₁, p₂, p₃} : set P)) (hp₁ : dist p₁ p = r) (hp₂ : dist p₂ p < r) (hp₃ : dist p₃ p = r) (hp₁p₃ : p₁ ≠ p₃) : sbtw ℝ p₁ p₂ p₃
begin refine ⟨h.wbtw_of_dist_eq_of_dist_le hp₁ hp₂.le hp₃ hp₁p₃, _, _⟩, { rintro rfl, exact hp₂.ne hp₁ }, { rintro rfl, exact hp₂.ne hp₃ } end
lemma
collinear.sbtw_of_dist_eq_of_dist_lt
analysis.convex
src/analysis/convex/strict_convex_between.lean
[ "analysis.convex.between", "analysis.convex.strict_convex_space" ]
[ "collinear", "sbtw" ]
Given three collinear points, two (not equal) with distance `r` from `p` and one with distance less than `r` from `p`, the third point is strictly between the other two points.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex_space (𝕜 E : Type*) [normed_linear_ordered_field 𝕜] [normed_add_comm_group E] [normed_space 𝕜 E] : Prop
(strict_convex_closed_ball : ∀ r : ℝ, 0 < r → strict_convex 𝕜 (closed_ball (0 : E) r))
class
strict_convex_space
analysis.convex
src/analysis/convex/strict_convex_space.lean
[ "analysis.convex.normed", "analysis.convex.strict", "analysis.normed.order.basic", "analysis.normed_space.add_torsor", "analysis.normed_space.pointwise", "analysis.normed_space.affine_isometry" ]
[ "normed_add_comm_group", "normed_linear_ordered_field", "normed_space", "strict_convex", "strict_convex_closed_ball" ]
A *strictly convex space* is a normed space where the closed balls are strictly convex. We only require balls of positive radius with center at the origin to be strictly convex in the definition, then prove that any closed ball is strictly convex in `strict_convex_closed_ball` below. See also `strict_convex_space.of_s...
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex_closed_ball [strict_convex_space 𝕜 E] (x : E) (r : ℝ) : strict_convex 𝕜 (closed_ball x r)
begin cases le_or_lt r 0 with hr hr, { exact (subsingleton_closed_ball x hr).strict_convex }, rw ← vadd_closed_ball_zero, exact (strict_convex_space.strict_convex_closed_ball r hr).vadd _, end
lemma
strict_convex_closed_ball
analysis.convex
src/analysis/convex/strict_convex_space.lean
[ "analysis.convex.normed", "analysis.convex.strict", "analysis.normed.order.basic", "analysis.normed_space.add_torsor", "analysis.normed_space.pointwise", "analysis.normed_space.affine_isometry" ]
[ "strict_convex", "strict_convex_space", "vadd_closed_ball_zero" ]
A closed ball in a strictly convex space is strictly convex.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex_space.of_strict_convex_closed_unit_ball [linear_map.compatible_smul E E 𝕜 ℝ] (h : strict_convex 𝕜 (closed_ball (0 : E) 1)) : strict_convex_space 𝕜 E
⟨λ r hr, by simpa only [smul_closed_unit_ball_of_nonneg hr.le] using h.smul r⟩
lemma
strict_convex_space.of_strict_convex_closed_unit_ball
analysis.convex
src/analysis/convex/strict_convex_space.lean
[ "analysis.convex.normed", "analysis.convex.strict", "analysis.normed.order.basic", "analysis.normed_space.add_torsor", "analysis.normed_space.pointwise", "analysis.normed_space.affine_isometry" ]
[ "linear_map.compatible_smul", "smul_closed_unit_ball_of_nonneg", "strict_convex", "strict_convex_space" ]
A real normed vector space is strictly convex provided that the unit ball is strictly convex.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex_space.of_norm_combo_lt_one (h : ∀ x y : E, ‖x‖ = 1 → ‖y‖ = 1 → x ≠ y → ∃ a b : ℝ, a + b = 1 ∧ ‖a • x + b • y‖ < 1) : strict_convex_space ℝ E
begin refine strict_convex_space.of_strict_convex_closed_unit_ball ℝ ((convex_closed_ball _ _).strict_convex' $ λ x hx y hy hne, _), rw [interior_closed_ball (0 : E) one_ne_zero, closed_ball_diff_ball, mem_sphere_zero_iff_norm] at hx hy, rcases h x y hx hy hne with ⟨a, b, hab, hlt⟩, use b, rwa [affine...
lemma
strict_convex_space.of_norm_combo_lt_one
analysis.convex
src/analysis/convex/strict_convex_space.lean
[ "analysis.convex.normed", "analysis.convex.strict", "analysis.normed.order.basic", "analysis.normed_space.add_torsor", "analysis.normed_space.pointwise", "analysis.normed_space.affine_isometry" ]
[ "affine_map.line_map_apply_module", "convex_closed_ball", "interior_closed_ball", "one_ne_zero", "strict_convex_space", "strict_convex_space.of_strict_convex_closed_unit_ball" ]
Strict convexity is equivalent to `‖a • x + b • y‖ < 1` for all `x` and `y` of norm at most `1` and all strictly positive `a` and `b` such that `a + b = 1`. This lemma shows that it suffices to check this for points of norm one and some `a`, `b` such that `a + b = 1`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex_space.of_norm_combo_ne_one (h : ∀ x y : E, ‖x‖ = 1 → ‖y‖ = 1 → x ≠ y → ∃ a b : ℝ, 0 ≤ a ∧ 0 ≤ b ∧ a + b = 1 ∧ ‖a • x + b • y‖ ≠ 1) : strict_convex_space ℝ E
begin refine strict_convex_space.of_strict_convex_closed_unit_ball ℝ ((convex_closed_ball _ _).strict_convex _), simp only [interior_closed_ball _ one_ne_zero, closed_ball_diff_ball, set.pairwise, frontier_closed_ball _ one_ne_zero, mem_sphere_zero_iff_norm], intros x hx y hy hne, rcases h x y hx hy hne...
lemma
strict_convex_space.of_norm_combo_ne_one
analysis.convex
src/analysis/convex/strict_convex_space.lean
[ "analysis.convex.normed", "analysis.convex.strict", "analysis.normed.order.basic", "analysis.normed_space.add_torsor", "analysis.normed_space.pointwise", "analysis.normed_space.affine_isometry" ]
[ "convex_closed_ball", "frontier_closed_ball", "interior_closed_ball", "one_ne_zero", "set.pairwise", "strict_convex", "strict_convex_space", "strict_convex_space.of_strict_convex_closed_unit_ball" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex_space.of_norm_add_ne_two (h : ∀ ⦃x y : E⦄, ‖x‖ = 1 → ‖y‖ = 1 → x ≠ y → ‖x + y‖ ≠ 2) : strict_convex_space ℝ E
begin refine strict_convex_space.of_norm_combo_ne_one (λ x y hx hy hne, ⟨1/2, 1/2, one_half_pos.le, one_half_pos.le, add_halves _, _⟩), rw [← smul_add, norm_smul, real.norm_of_nonneg one_half_pos.le, one_div, ← div_eq_inv_mul, ne.def, div_eq_one_iff_eq (two_ne_zero' ℝ)], exact h hx hy hne, end
lemma
strict_convex_space.of_norm_add_ne_two
analysis.convex
src/analysis/convex/strict_convex_space.lean
[ "analysis.convex.normed", "analysis.convex.strict", "analysis.normed.order.basic", "analysis.normed_space.add_torsor", "analysis.normed_space.pointwise", "analysis.normed_space.affine_isometry" ]
[ "add_halves", "div_eq_inv_mul", "div_eq_one_iff_eq", "norm_smul", "one_div", "real.norm_of_nonneg", "smul_add", "strict_convex_space", "strict_convex_space.of_norm_combo_ne_one", "two_ne_zero'" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex_space.of_pairwise_sphere_norm_ne_two (h : (sphere (0 : E) 1).pairwise $ λ x y, ‖x + y‖ ≠ 2) : strict_convex_space ℝ E
strict_convex_space.of_norm_add_ne_two $ λ x y hx hy, h (mem_sphere_zero_iff_norm.2 hx) (mem_sphere_zero_iff_norm.2 hy)
lemma
strict_convex_space.of_pairwise_sphere_norm_ne_two
analysis.convex
src/analysis/convex/strict_convex_space.lean
[ "analysis.convex.normed", "analysis.convex.strict", "analysis.normed.order.basic", "analysis.normed_space.add_torsor", "analysis.normed_space.pointwise", "analysis.normed_space.affine_isometry" ]
[ "pairwise", "strict_convex_space", "strict_convex_space.of_norm_add_ne_two" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
strict_convex_space.of_norm_add (h : ∀ x y : E, ‖x‖ = 1 → ‖y‖ = 1 → ‖x + y‖ = 2 → same_ray ℝ x y) : strict_convex_space ℝ E
begin refine strict_convex_space.of_pairwise_sphere_norm_ne_two (λ x hx y hy, mt $ λ h₂, _), rw mem_sphere_zero_iff_norm at hx hy, exact (same_ray_iff_of_norm_eq (hx.trans hy.symm)).1 (h x y hx hy h₂) end
lemma
strict_convex_space.of_norm_add
analysis.convex
src/analysis/convex/strict_convex_space.lean
[ "analysis.convex.normed", "analysis.convex.strict", "analysis.normed.order.basic", "analysis.normed_space.add_torsor", "analysis.normed_space.pointwise", "analysis.normed_space.affine_isometry" ]
[ "same_ray", "same_ray_iff_of_norm_eq", "strict_convex_space", "strict_convex_space.of_pairwise_sphere_norm_ne_two" ]
If `‖x + y‖ = ‖x‖ + ‖y‖` implies that `x y : E` are in the same ray, then `E` is a strictly convex space. See also a more
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
combo_mem_ball_of_ne (hx : x ∈ closed_ball z r) (hy : y ∈ closed_ball z r) (hne : x ≠ y) (ha : 0 < a) (hb : 0 < b) (hab : a + b = 1) : a • x + b • y ∈ ball z r
begin rcases eq_or_ne r 0 with rfl|hr, { rw [closed_ball_zero, mem_singleton_iff] at hx hy, exact (hne (hx.trans hy.symm)).elim }, { simp only [← interior_closed_ball _ hr] at hx hy ⊢, exact strict_convex_closed_ball ℝ z r hx hy hne ha hb hab } end
lemma
combo_mem_ball_of_ne
analysis.convex
src/analysis/convex/strict_convex_space.lean
[ "analysis.convex.normed", "analysis.convex.strict", "analysis.normed.order.basic", "analysis.normed_space.add_torsor", "analysis.normed_space.pointwise", "analysis.normed_space.affine_isometry" ]
[ "eq_or_ne", "interior_closed_ball", "strict_convex_closed_ball" ]
If `x ≠ y` belong to the same closed ball, then a convex combination of `x` and `y` with positive coefficients belongs to the corresponding open ball.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
open_segment_subset_ball_of_ne (hx : x ∈ closed_ball z r) (hy : y ∈ closed_ball z r) (hne : x ≠ y) : open_segment ℝ x y ⊆ ball z r
(open_segment_subset_iff _).2 $ λ a b, combo_mem_ball_of_ne hx hy hne
lemma
open_segment_subset_ball_of_ne
analysis.convex
src/analysis/convex/strict_convex_space.lean
[ "analysis.convex.normed", "analysis.convex.strict", "analysis.normed.order.basic", "analysis.normed_space.add_torsor", "analysis.normed_space.pointwise", "analysis.normed_space.affine_isometry" ]
[ "combo_mem_ball_of_ne", "open_segment", "open_segment_subset_iff" ]
If `x ≠ y` belong to the same closed ball, then the open segment with endpoints `x` and `y` is included in the corresponding open ball.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
norm_combo_lt_of_ne (hx : ‖x‖ ≤ r) (hy : ‖y‖ ≤ r) (hne : x ≠ y) (ha : 0 < a) (hb : 0 < b) (hab : a + b = 1) : ‖a • x + b • y‖ < r
begin simp only [← mem_ball_zero_iff, ← mem_closed_ball_zero_iff] at hx hy ⊢, exact combo_mem_ball_of_ne hx hy hne ha hb hab end
lemma
norm_combo_lt_of_ne
analysis.convex
src/analysis/convex/strict_convex_space.lean
[ "analysis.convex.normed", "analysis.convex.strict", "analysis.normed.order.basic", "analysis.normed_space.add_torsor", "analysis.normed_space.pointwise", "analysis.normed_space.affine_isometry" ]
[ "combo_mem_ball_of_ne" ]
If `x` and `y` are two distinct vectors of norm at most `r`, then a convex combination of `x` and `y` with positive coefficients has norm strictly less than `r`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
norm_add_lt_of_not_same_ray (h : ¬same_ray ℝ x y) : ‖x + y‖ < ‖x‖ + ‖y‖
begin simp only [same_ray_iff_inv_norm_smul_eq, not_or_distrib, ← ne.def] at h, rcases h with ⟨hx, hy, hne⟩, rw ← norm_pos_iff at hx hy, have hxy : 0 < ‖x‖ + ‖y‖ := add_pos hx hy, have := combo_mem_ball_of_ne (inv_norm_smul_mem_closed_unit_ball x) (inv_norm_smul_mem_closed_unit_ball y) hne (div_pos hx hxy...
lemma
norm_add_lt_of_not_same_ray
analysis.convex
src/analysis/convex/strict_convex_space.lean
[ "analysis.convex.normed", "analysis.convex.strict", "analysis.normed.order.basic", "analysis.normed_space.add_torsor", "analysis.normed_space.pointwise", "analysis.normed_space.affine_isometry" ]
[ "add_div", "combo_mem_ball_of_ne", "div_eq_inv_mul", "div_lt_one", "div_pos", "div_self", "inv_norm_smul_mem_closed_unit_ball", "norm_smul", "not_or_distrib", "real.norm_of_nonneg", "same_ray", "same_ray_iff_inv_norm_smul_eq", "smul_add", "smul_inv_smul₀" ]
In a strictly convex space, if `x` and `y` are not in the same ray, then `‖x + y‖ < ‖x‖ + ‖y‖`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
lt_norm_sub_of_not_same_ray (h : ¬same_ray ℝ x y) : ‖x‖ - ‖y‖ < ‖x - y‖
begin nth_rewrite 0 ←sub_add_cancel x y at ⊢ h, exact sub_lt_iff_lt_add.2 (norm_add_lt_of_not_same_ray $ λ H', h $ H'.add_left same_ray.rfl), end
lemma
lt_norm_sub_of_not_same_ray
analysis.convex
src/analysis/convex/strict_convex_space.lean
[ "analysis.convex.normed", "analysis.convex.strict", "analysis.normed.order.basic", "analysis.normed_space.add_torsor", "analysis.normed_space.pointwise", "analysis.normed_space.affine_isometry" ]
[ "norm_add_lt_of_not_same_ray", "same_ray", "same_ray.rfl" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
abs_lt_norm_sub_of_not_same_ray (h : ¬same_ray ℝ x y) : |‖x‖ - ‖y‖| < ‖x - y‖
begin refine abs_sub_lt_iff.2 ⟨lt_norm_sub_of_not_same_ray h, _⟩, rw norm_sub_rev, exact lt_norm_sub_of_not_same_ray (mt same_ray.symm h), end
lemma
abs_lt_norm_sub_of_not_same_ray
analysis.convex
src/analysis/convex/strict_convex_space.lean
[ "analysis.convex.normed", "analysis.convex.strict", "analysis.normed.order.basic", "analysis.normed_space.add_torsor", "analysis.normed_space.pointwise", "analysis.normed_space.affine_isometry" ]
[ "lt_norm_sub_of_not_same_ray", "same_ray", "same_ray.symm" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
same_ray_iff_norm_add : same_ray ℝ x y ↔ ‖x + y‖ = ‖x‖ + ‖y‖
⟨same_ray.norm_add, λ h, not_not.1 $ λ h', (norm_add_lt_of_not_same_ray h').ne h⟩
lemma
same_ray_iff_norm_add
analysis.convex
src/analysis/convex/strict_convex_space.lean
[ "analysis.convex.normed", "analysis.convex.strict", "analysis.normed.order.basic", "analysis.normed_space.add_torsor", "analysis.normed_space.pointwise", "analysis.normed_space.affine_isometry" ]
[ "norm_add_lt_of_not_same_ray", "same_ray" ]
In a strictly convex space, two vectors `x`, `y` are in the same ray if and only if the triangle inequality for `x` and `y` becomes an equality.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
eq_of_norm_eq_of_norm_add_eq (h₁ : ‖x‖ = ‖y‖) (h₂ : ‖x + y‖ = ‖x‖ + ‖y‖) : x = y
(same_ray_iff_norm_add.mpr h₂).eq_of_norm_eq h₁
lemma
eq_of_norm_eq_of_norm_add_eq
analysis.convex
src/analysis/convex/strict_convex_space.lean
[ "analysis.convex.normed", "analysis.convex.strict", "analysis.normed.order.basic", "analysis.normed_space.add_torsor", "analysis.normed_space.pointwise", "analysis.normed_space.affine_isometry" ]
[]
If `x` and `y` are two vectors in a strictly convex space have the same norm and the norm of their sum is equal to the sum of their norms, then they are equal.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
not_same_ray_iff_norm_add_lt : ¬ same_ray ℝ x y ↔ ‖x + y‖ < ‖x‖ + ‖y‖
same_ray_iff_norm_add.not.trans (norm_add_le _ _).lt_iff_ne.symm
lemma
not_same_ray_iff_norm_add_lt
analysis.convex
src/analysis/convex/strict_convex_space.lean
[ "analysis.convex.normed", "analysis.convex.strict", "analysis.normed.order.basic", "analysis.normed_space.add_torsor", "analysis.normed_space.pointwise", "analysis.normed_space.affine_isometry" ]
[ "same_ray" ]
In a strictly convex space, two vectors `x`, `y` are not in the same ray if and only if the triangle inequality for `x` and `y` is strict.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
same_ray_iff_norm_sub : same_ray ℝ x y ↔ ‖x - y‖ = |‖x‖ - ‖y‖|
⟨same_ray.norm_sub, λ h, not_not.1 $ λ h', (abs_lt_norm_sub_of_not_same_ray h').ne' h⟩
lemma
same_ray_iff_norm_sub
analysis.convex
src/analysis/convex/strict_convex_space.lean
[ "analysis.convex.normed", "analysis.convex.strict", "analysis.normed.order.basic", "analysis.normed_space.add_torsor", "analysis.normed_space.pointwise", "analysis.normed_space.affine_isometry" ]
[ "abs_lt_norm_sub_of_not_same_ray", "same_ray" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
not_same_ray_iff_abs_lt_norm_sub : ¬ same_ray ℝ x y ↔ |‖x‖ - ‖y‖| < ‖x - y‖
same_ray_iff_norm_sub.not.trans $ ne_comm.trans (abs_norm_sub_norm_le _ _).lt_iff_ne.symm
lemma
not_same_ray_iff_abs_lt_norm_sub
analysis.convex
src/analysis/convex/strict_convex_space.lean
[ "analysis.convex.normed", "analysis.convex.strict", "analysis.normed.order.basic", "analysis.normed_space.add_torsor", "analysis.normed_space.pointwise", "analysis.normed_space.affine_isometry" ]
[ "same_ray" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83