imo.imo1994_q1 ⟷ Archive.Imo.Imo1994Q1

mathlib commit https://github.com/leanprover-community/mathlib/commit/65a1391a0106c9204fe45bc73a039f056558cb83

@@ -4,7 +4,7 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Antoine Labelle
 -/
 import Algebra.BigOperators.Basic
-import Algebra.BigOperators.Order
+import Algebra.Order.BigOperators.Group.Finset
 import Data.Fintype.BigOperators
 import Data.Finset.Sort
 import Data.Fin.Interval

mathlib commit https://github.com/leanprover-community/mathlib/commit/65a1391a0106c9204fe45bc73a039f056558cb83

@@ -55,7 +55,7 @@ end imo1994_q1
 
 open imo1994_q1
 
-/- ./././Mathport/Syntax/Translate/Basic.lean:641:2: warning: expanding binder collection (a b «expr ∈ » A) -/
+/- ./././Mathport/Syntax/Translate/Basic.lean:642:2: warning: expanding binder collection (a b «expr ∈ » A) -/
 theorem imo1994_q1 (n : ℕ) (m : ℕ) (A : Finset ℕ) (hm : A.card = m + 1)
     (hrange : ∀ a ∈ A, 0 < a ∧ a ≤ n)
     (hadd : ∀ (a) (_ : a ∈ A) (b) (_ : b ∈ A), a + b ≤ n → a + b ∈ A) :

mathlib commit https://github.com/leanprover-community/mathlib/commit/65a1391a0106c9204fe45bc73a039f056558cb83

@@ -43,7 +43,7 @@ namespace imo1994_q1
 theorem tedious (m : ℕ) (k : Fin (m + 1)) : m - (m + (m + 1 - ↑k)) % (m + 1) = ↑k :=
   by
   cases' k with k hk
-  rw [Nat.lt_succ_iff, le_iff_exists_add] at hk 
+  rw [Nat.lt_succ_iff, le_iff_exists_add] at hk
   rcases hk with ⟨c, rfl⟩
   have : k + c + (k + c + 1 - k) = c + (k + c + 1) := by
     simp only [add_assoc, add_tsub_cancel_left, add_left_comm]
@@ -88,18 +88,18 @@ theorem imo1994_q1 (n : ℕ) (m : ℕ) (A : Finset ℕ) (hm : A.card = m + 1)
     ⟨fun i => a i + a (rev k), by
       apply injective_of_le_imp_le
       intro i j hij
-      rwa [add_le_add_iff_right, a.map_rel_iff] at hij ⟩
+      rwa [add_le_add_iff_right, a.map_rel_iff] at hij⟩
   -- Proof that the `f i` are greater than `a (rev k)` for `i ≤ k`
   have hf : map f (Icc 0 k) ⊆ map a.to_embedding (Ioc (rev k) (Fin.last m)) :=
     by
     intro x hx
-    simp only [Equiv.subLeft_apply] at h 
+    simp only [Equiv.subLeft_apply] at h
     simp only [mem_map, f, mem_Icc, mem_Ioc, Fin.zero_le', true_and_iff, Equiv.subLeft_apply,
       Function.Embedding.coeFn_mk, exists_prop, RelEmbedding.coe_toEmbedding] at hx ⊢
     rcases hx with ⟨i, ⟨hi, rfl⟩⟩
     have h1 : a i + a (Fin.last m - k) ≤ n := by linarith only [h, a.monotone hi]
     have h2 : a i + a (Fin.last m - k) ∈ A := hadd _ (ha _) _ (ha _) h1
-    rw [← mem_coe, ← range_order_emb_of_fin A hm, Set.mem_range] at h2 
+    rw [← mem_coe, ← range_order_emb_of_fin A hm, Set.mem_range] at h2
     cases' h2 with j hj
     refine' ⟨j, ⟨_, Fin.le_last j⟩, hj⟩
     rw [← a.strict_mono.lt_iff_lt, hj]

mathlib commit https://github.com/leanprover-community/mathlib/commit/65a1391a0106c9204fe45bc73a039f056558cb83

@@ -82,7 +82,7 @@ theorem imo1994_q1 (n : ℕ) (m : ℕ) (A : Finset ℕ) (hm : A.card = m + 1)
     _ = (m + 1) * (n + 1) := by rw [sum_const, card_fin, Nat.nsmul_eq_mul]
   -- It remains to prove the key inequality, by contradiction
   rintro k -
-  by_contra' h : a k + a (rev k) < n + 1
+  by_contra! h : a k + a (rev k) < n + 1
   -- We exhibit `k+1` elements of `A` greater than `a (rev k)`
   set f : Fin (m + 1) ↪ ℕ :=
     ⟨fun i => a i + a (rev k), by

mathlib commit https://github.com/leanprover-community/mathlib/commit/ce64cd319bb6b3e82f31c2d38e79080d377be451

@@ -3,13 +3,13 @@ Copyright (c) 2021 Antoine Labelle. All rights reserved.
 Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Antoine Labelle
 -/
-import Mathbin.Algebra.BigOperators.Basic
-import Mathbin.Algebra.BigOperators.Order
-import Mathbin.Data.Fintype.BigOperators
-import Mathbin.Data.Finset.Sort
-import Mathbin.Data.Fin.Interval
+import Algebra.BigOperators.Basic
+import Algebra.BigOperators.Order
+import Data.Fintype.BigOperators
+import Data.Finset.Sort
+import Data.Fin.Interval
 import Mathbin.Tactic.Linarith.Default
-import Mathbin.Tactic.ByContra
+import Tactic.ByContra
 
 #align_import imo.imo1994_q1 from "leanprover-community/mathlib"@"08b081ea92d80e3a41f899eea36ef6d56e0f1db0"
 
@@ -55,7 +55,7 @@ end imo1994_q1
 
 open imo1994_q1
 
-/- ./././Mathport/Syntax/Translate/Basic.lean:635:2: warning: expanding binder collection (a b «expr ∈ » A) -/
+/- ./././Mathport/Syntax/Translate/Basic.lean:641:2: warning: expanding binder collection (a b «expr ∈ » A) -/
 theorem imo1994_q1 (n : ℕ) (m : ℕ) (A : Finset ℕ) (hm : A.card = m + 1)
     (hrange : ∀ a ∈ A, 0 < a ∧ a ≤ n)
     (hadd : ∀ (a) (_ : a ∈ A) (b) (_ : b ∈ A), a + b ≤ n → a + b ∈ A) :

mathlib commit https://github.com/leanprover-community/mathlib/commit/63721b2c3eba6c325ecf8ae8cca27155a4f6306f

@@ -94,7 +94,7 @@ theorem imo1994_q1 (n : ℕ) (m : ℕ) (A : Finset ℕ) (hm : A.card = m + 1)
     by
     intro x hx
     simp only [Equiv.subLeft_apply] at h 
-    simp only [mem_map, f, mem_Icc, mem_Ioc, Fin.zero_le, true_and_iff, Equiv.subLeft_apply,
+    simp only [mem_map, f, mem_Icc, mem_Ioc, Fin.zero_le', true_and_iff, Equiv.subLeft_apply,
       Function.Embedding.coeFn_mk, exists_prop, RelEmbedding.coe_toEmbedding] at hx ⊢
     rcases hx with ⟨i, ⟨hi, rfl⟩⟩
     have h1 : a i + a (Fin.last m - k) ≤ n := by linarith only [h, a.monotone hi]

mathlib commit https://github.com/leanprover-community/mathlib/commit/8ea5598db6caeddde6cb734aa179cc2408dbd345

@@ -2,11 +2,6 @@
 Copyright (c) 2021 Antoine Labelle. All rights reserved.
 Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Antoine Labelle
-
-! This file was ported from Lean 3 source module imo.imo1994_q1
-! leanprover-community/mathlib commit 08b081ea92d80e3a41f899eea36ef6d56e0f1db0
-! Please do not edit these lines, except to modify the commit id
-! if you have ported upstream changes.
 -/
 import Mathbin.Algebra.BigOperators.Basic
 import Mathbin.Algebra.BigOperators.Order
@@ -16,6 +11,8 @@ import Mathbin.Data.Fin.Interval
 import Mathbin.Tactic.Linarith.Default
 import Mathbin.Tactic.ByContra
 
+#align_import imo.imo1994_q1 from "leanprover-community/mathlib"@"08b081ea92d80e3a41f899eea36ef6d56e0f1db0"
+
 /-!
 # IMO 1994 Q1
 
@@ -58,7 +55,7 @@ end imo1994_q1
 
 open imo1994_q1
 
-/- ./././Mathport/Syntax/Translate/Basic.lean:638:2: warning: expanding binder collection (a b «expr ∈ » A) -/
+/- ./././Mathport/Syntax/Translate/Basic.lean:635:2: warning: expanding binder collection (a b «expr ∈ » A) -/
 theorem imo1994_q1 (n : ℕ) (m : ℕ) (A : Finset ℕ) (hm : A.card = m + 1)
     (hrange : ∀ a ∈ A, 0 < a ∧ a ≤ n)
     (hadd : ∀ (a) (_ : a ∈ A) (b) (_ : b ∈ A), a + b ≤ n → a + b ∈ A) :

mathlib commit https://github.com/leanprover-community/mathlib/commit/bf2428c9486c407ca38b5b3fb10b87dad0bc99fa

@@ -4,7 +4,7 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Antoine Labelle
 
 ! This file was ported from Lean 3 source module imo.imo1994_q1
-! leanprover-community/mathlib commit 308826471968962c6b59c7ff82a22757386603e3
+! leanprover-community/mathlib commit 08b081ea92d80e3a41f899eea36ef6d56e0f1db0
 ! Please do not edit these lines, except to modify the commit id
 ! if you have ported upstream changes.
 -/
@@ -19,6 +19,9 @@ import Mathbin.Tactic.ByContra
 /-!
 # IMO 1994 Q1
 
+> THIS FILE IS SYNCHRONIZED WITH MATHLIB4.
+> Any changes to this file require a corresponding PR to mathlib4.
+
 Let `m` and `n` be two positive integers.
 Let `a₁, a₂, ..., aₘ` be `m` different numbers from the set `{1, 2, ..., n}`
 such that for any two indices `i` and `j` with `1 ≤ i ≤ j ≤ m` and `aᵢ + aⱼ ≤ n`,

mathlib commit https://github.com/leanprover-community/mathlib/commit/a3e83f0fa4391c8740f7d773a7a9b74e311ae2a3

@@ -67,7 +67,7 @@ theorem imo1994_q1 (n : ℕ) (m : ℕ) (A : Finset ℕ) (hm : A.card = m + 1)
   set rev := Equiv.subLeft (Fin.last m)
   -- `i ↦ m-i`
   -- We reindex the sum by fin (m+1)
-  have : (∑ x in A, x) = ∑ i : Fin (m + 1), a i :=
+  have : ∑ x in A, x = ∑ i : Fin (m + 1), a i :=
     by
     convert sum_image fun x hx y hy => (OrderEmbedding.eq_iff_eq a).1
     rw [← coe_inj]; simp
@@ -75,10 +75,10 @@ theorem imo1994_q1 (n : ℕ) (m : ℕ) (A : Finset ℕ) (hm : A.card = m + 1)
   -- The main proof is a simple calculation by rearranging one of the two sums
   suffices hpair : ∀ k ∈ univ, a k + a (rev k) ≥ n + 1
   calc
-    (2 * ∑ i : Fin (m + 1), a i) = (∑ i : Fin (m + 1), a i) + ∑ i : Fin (m + 1), a i := two_mul _
-    _ = (∑ i : Fin (m + 1), a i) + ∑ i : Fin (m + 1), a (rev i) := by rw [Equiv.sum_comp rev]
-    _ = ∑ i : Fin (m + 1), a i + a (rev i) := sum_add_distrib.symm
-    _ ≥ ∑ i : Fin (m + 1), n + 1 := (sum_le_sum hpair)
+    2 * ∑ i : Fin (m + 1), a i = ∑ i : Fin (m + 1), a i + ∑ i : Fin (m + 1), a i := two_mul _
+    _ = ∑ i : Fin (m + 1), a i + ∑ i : Fin (m + 1), a (rev i) := by rw [Equiv.sum_comp rev]
+    _ = ∑ i : Fin (m + 1), (a i + a (rev i)) := sum_add_distrib.symm
+    _ ≥ ∑ i : Fin (m + 1), (n + 1) := (sum_le_sum hpair)
     _ = (m + 1) * (n + 1) := by rw [sum_const, card_fin, Nat.nsmul_eq_mul]
   -- It remains to prove the key inequality, by contradiction
   rintro k -

mathlib commit https://github.com/leanprover-community/mathlib/commit/7e5137f579de09a059a5ce98f364a04e221aabf0

@@ -80,7 +80,6 @@ theorem imo1994_q1 (n : ℕ) (m : ℕ) (A : Finset ℕ) (hm : A.card = m + 1)
     _ = ∑ i : Fin (m + 1), a i + a (rev i) := sum_add_distrib.symm
     _ ≥ ∑ i : Fin (m + 1), n + 1 := (sum_le_sum hpair)
     _ = (m + 1) * (n + 1) := by rw [sum_const, card_fin, Nat.nsmul_eq_mul]
-    
   -- It remains to prove the key inequality, by contradiction
   rintro k -
   by_contra' h : a k + a (rev k) < n + 1

mathlib commit https://github.com/leanprover-community/mathlib/commit/31c24aa72e7b3e5ed97a8412470e904f82b81004

@@ -55,7 +55,7 @@ end imo1994_q1
 
 open imo1994_q1
 
-/- ./././Mathport/Syntax/Translate/Basic.lean:635:2: warning: expanding binder collection (a b «expr ∈ » A) -/
+/- ./././Mathport/Syntax/Translate/Basic.lean:638:2: warning: expanding binder collection (a b «expr ∈ » A) -/
 theorem imo1994_q1 (n : ℕ) (m : ℕ) (A : Finset ℕ) (hm : A.card = m + 1)
     (hrange : ∀ a ∈ A, 0 < a ∧ a ≤ n)
     (hadd : ∀ (a) (_ : a ∈ A) (b) (_ : b ∈ A), a + b ≤ n → a + b ∈ A) :

mathlib commit https://github.com/leanprover-community/mathlib/commit/a3209ddf94136d36e5e5c624b10b2a347cc9d090

Co-authored-by: Moritz Firsching <firsching@google.com>

@@ -67,7 +67,7 @@ theorem imo1994_q1 (n : ℕ) (m : ℕ) (A : Finset ℕ) (hm : A.card = m + 1)
     2 * ∑ i : Fin (m + 1), a i = ∑ i : Fin (m + 1), a i + ∑ i : Fin (m + 1), a i := two_mul _
     _ = ∑ i : Fin (m + 1), a i + ∑ i : Fin (m + 1), a (rev i) := by rw [Equiv.sum_comp rev]
     _ = ∑ i : Fin (m + 1), (a i + a (rev i)) := sum_add_distrib.symm
-    _ ≥ ∑ i : Fin (m + 1), (n + 1) := (sum_le_sum hpair)
+    _ ≥ ∑ i : Fin (m + 1), (n + 1) := sum_le_sum hpair
     _ = (m + 1) * (n + 1) := by rw [sum_const, card_fin, Nat.nsmul_eq_mul]
   -- It remains to prove the key inequality, by contradiction
   rintro k -

Take the content of

• some of Algebra.BigOperators.List.Basic
• some of Algebra.BigOperators.List.Lemmas
• some of Algebra.BigOperators.Multiset.Basic
• some of Algebra.BigOperators.Multiset.Lemmas
• Algebra.BigOperators.Multiset.Order
• Algebra.BigOperators.Order

and sort it into six files:

• Algebra.Order.BigOperators.Group.List. I credit Yakov for https://github.com/leanprover-community/mathlib/pull/8543.
• Algebra.Order.BigOperators.Group.Multiset. Copyright inherited from Algebra.BigOperators.Multiset.Order.
• Algebra.Order.BigOperators.Group.Finset. Copyright inherited from Algebra.BigOperators.Order.
• Algebra.Order.BigOperators.Ring.List. I credit Stuart for https://github.com/leanprover-community/mathlib/pull/10184.
• Algebra.Order.BigOperators.Ring.Multiset. I credit Ruben for https://github.com/leanprover-community/mathlib/pull/8787.
• Algebra.Order.BigOperators.Ring.Finset. I credit Floris for https://github.com/leanprover-community/mathlib/pull/1294.

Here are the design decisions at play:

• Pure algebra and big operators algebra shouldn't import (algebraic) order theory. This PR makes that better, but not perfect because we still import Data.Nat.Order.Basic in a few List files.
• It's Algebra.Order.BigOperators instead of Algebra.BigOperators.Order because algebraic order theory is more of a theory than big operators algebra. Another reason is that algebraic order theory is the only way to mix pure order and pure algebra, while there are more ways to mix pure finiteness and pure algebra than just big operators.
• There are separate files for group/monoid lemmas vs ring lemmas. Groups/monoids are the natural setup for big operators, so their lemmas shouldn't be mixed with ring lemmas that involves both addition and multiplication. As a result, everything under Algebra.Order.BigOperators.Group should be additivisable (except a few Nat- or Int-specific lemmas). In contrast, things under Algebra.Order.BigOperators.Ring are more prone to having heavy imports.
• Lemmas are separated according to List vs Multiset vs Finset. This is not strictly necessary, and can be relaxed in cases where there aren't that many lemmas to be had. As an example, I could split out the AbsoluteValue lemmas from Algebra.Order.BigOperators.Ring.Finset to a file Algebra.Order.BigOperators.Ring.AbsoluteValue and it could stay this way until too many lemmas are in this file (or a split is needed for import reasons), in which case we would need files Algebra.Order.BigOperators.Ring.AbsoluteValue.Finset, Algebra.Order.BigOperators.Ring.AbsoluteValue.Multiset, etc...
• Finsupp big operator and finprod/finsum order lemmas also belong in Algebra.Order.BigOperators. I haven't done so in this PR because the diff is big enough like that.

@@ -3,13 +3,10 @@ Copyright (c) 2021 Antoine Labelle. All rights reserved.
 Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Antoine Labelle
 -/
-import Mathlib.Algebra.BigOperators.Basic
-import Mathlib.Algebra.BigOperators.Order
-import Mathlib.Data.Fintype.BigOperators
+import Mathlib.Algebra.Order.BigOperators.Group.Finset
 import Mathlib.Data.Finset.Sort
 import Mathlib.Data.Fin.Interval
 import Mathlib.Tactic.Linarith
-import Mathlib.Tactic.ByContra
 
 #align_import imo.imo1994_q1 from "leanprover-community/mathlib"@"308826471968962c6b59c7ff82a22757386603e3"
 

Co-authored-by: Scott Morrison <scott.morrison@gmail.com>

@@ -63,7 +63,7 @@ theorem imo1994_q1 (n : ℕ) (m : ℕ) (A : Finset ℕ) (hm : A.card = m + 1)
   -- We reindex the sum by fin (m+1)
   have : ∑ x in A, x = ∑ i : Fin (m + 1), a i := by
     convert sum_image (α := ℕ) (β := ℕ) fun x _ y _ => (OrderEmbedding.eq_iff_eq a).1
-    rw [← coe_inj]; simp
+    rw [← coe_inj]; simp [a]
   rw [this]; clear this
   -- The main proof is a simple calculation by rearranging one of the two sums
   suffices hpair : ∀ k ∈ univ, a k + a (rev k) ≥ n + 1 by calc
@@ -84,11 +84,11 @@ theorem imo1994_q1 (n : ℕ) (m : ℕ) (A : Finset ℕ) (hm : A.card = m + 1)
   -- Proof that the `f i` are greater than `a (rev k)` for `i ≤ k`
   have hf : map f (Icc 0 k) ⊆ map a.toEmbedding (Ioc (rev k) (Fin.last m)) := by
     intro x hx
-    simp only [Equiv.subLeft_apply] at h
+    simp only [Equiv.subLeft_apply, a, rev] at h
     simp only [mem_map, mem_Icc, mem_Ioc, Fin.zero_le, true_and_iff, Equiv.subLeft_apply,
-      Function.Embedding.coeFn_mk, exists_prop, RelEmbedding.coe_toEmbedding] at hx ⊢
+      Function.Embedding.coeFn_mk, exists_prop, RelEmbedding.coe_toEmbedding, f, rev] at hx ⊢
     rcases hx with ⟨i, ⟨hi, rfl⟩⟩
-    have h1 : a i + a (Fin.last m - k) ≤ n := by linarith only [h, a.monotone hi]
+    have h1 : a i + a (Fin.last m - k) ≤ n := by unfold_let; linarith only [h, a.monotone hi]
     have h2 : a i + a (Fin.last m - k) ∈ A := hadd _ (ha _) _ (ha _) h1
     rw [← mem_coe, ← range_orderEmbOfFin A hm, Set.mem_range] at h2
     cases' h2 with j hj
@@ -96,5 +96,5 @@ theorem imo1994_q1 (n : ℕ) (m : ℕ) (A : Finset ℕ) (hm : A.card = m + 1)
     rw [← a.strictMono.lt_iff_lt, hj]
     simpa using (hrange (a i) (ha i)).1
   -- A set of size `k+1` embed in one of size `k`, which yields a contradiction
-  simpa [Fin.coe_sub, tedious] using card_le_card hf
+  simpa [Fin.coe_sub, tedious, rev] using card_le_card hf
 #align imo1994_q1 imo1994_q1

No changes to tactic file, it's just boring fixes throughout the library.

This follows on from #6964.

Co-authored-by: sgouezel <sebastien.gouezel@univ-rennes1.fr> Co-authored-by: Eric Wieser <wieser.eric@gmail.com>

@@ -66,8 +66,7 @@ theorem imo1994_q1 (n : ℕ) (m : ℕ) (A : Finset ℕ) (hm : A.card = m + 1)
     rw [← coe_inj]; simp
   rw [this]; clear this
   -- The main proof is a simple calculation by rearranging one of the two sums
-  suffices hpair : ∀ k ∈ univ, a k + a (rev k) ≥ n + 1
-  calc
+  suffices hpair : ∀ k ∈ univ, a k + a (rev k) ≥ n + 1 by calc
     2 * ∑ i : Fin (m + 1), a i = ∑ i : Fin (m + 1), a i + ∑ i : Fin (m + 1), a i := two_mul _
     _ = ∑ i : Fin (m + 1), a i + ∑ i : Fin (m + 1), a (rev i) := by rw [Equiv.sum_comp rev]
     _ = ∑ i : Fin (m + 1), (a i + a (rev i)) := sum_add_distrib.symm

Change a few lemma names that have historically bothered me.

• Finset.card_le_of_subset → Finset.card_le_card
• Multiset.card_le_of_le → Multiset.card_le_card
• Multiset.card_lt_of_lt → Multiset.card_lt_card
• Set.ncard_le_of_subset → Set.ncard_le_ncard
• Finset.image_filter → Finset.filter_image
• CompleteLattice.finset_sup_compact_of_compact → CompleteLattice.isCompactElement_finset_sup

@@ -97,5 +97,5 @@ theorem imo1994_q1 (n : ℕ) (m : ℕ) (A : Finset ℕ) (hm : A.card = m + 1)
     rw [← a.strictMono.lt_iff_lt, hj]
     simpa using (hrange (a i) (ha i)).1
   -- A set of size `k+1` embed in one of size `k`, which yields a contradiction
-  simpa [Fin.coe_sub, tedious] using card_le_of_subset hf
+  simpa [Fin.coe_sub, tedious] using card_le_card hf
 #align imo1994_q1 imo1994_q1

Search for [∀∃].*(_ and manually replace some occurrences with more readable versions. In case of ∀, the new expressions are defeq to the old ones. In case of ∃, they differ by exists_prop.

In some rare cases, golf proofs that needed fixing.

@@ -53,7 +53,7 @@ open Imo1994Q1
 
 theorem imo1994_q1 (n : ℕ) (m : ℕ) (A : Finset ℕ) (hm : A.card = m + 1)
     (hrange : ∀ a ∈ A, 0 < a ∧ a ≤ n)
-    (hadd : ∀ (a) (_ : a ∈ A) (b) (_ : b ∈ A), a + b ≤ n → a + b ∈ A) :
+    (hadd : ∀ a ∈ A, ∀ b ∈ A, a + b ≤ n → a + b ∈ A) :
     (m + 1) * (n + 1) ≤ 2 * ∑ x in A, x := by
   set a := orderEmbOfFin A hm
   -- We sort the elements of `A`

To fit with the "please try harder" convention of ! tactics.

Co-authored-by: Scott Morrison <scott.morrison@gmail.com>

@@ -75,7 +75,7 @@ theorem imo1994_q1 (n : ℕ) (m : ℕ) (A : Finset ℕ) (hm : A.card = m + 1)
     _ = (m + 1) * (n + 1) := by rw [sum_const, card_fin, Nat.nsmul_eq_mul]
   -- It remains to prove the key inequality, by contradiction
   rintro k -
-  by_contra' h : a k + a (rev k) < n + 1
+  by_contra! h : a k + a (rev k) < n + 1
   -- We exhibit `k+1` elements of `A` greater than `a (rev k)`
   set f : Fin (m + 1) ↪ ℕ :=
     ⟨fun i => a i + a (rev k), by

@@ -89,11 +89,7 @@ theorem imo1994_q1 (n : ℕ) (m : ℕ) (A : Finset ℕ) (hm : A.card = m + 1)
     simp only [mem_map, mem_Icc, mem_Ioc, Fin.zero_le, true_and_iff, Equiv.subLeft_apply,
       Function.Embedding.coeFn_mk, exists_prop, RelEmbedding.coe_toEmbedding] at hx ⊢
     rcases hx with ⟨i, ⟨hi, rfl⟩⟩
-    have h1 : a i + a (Fin.last m - k) ≤ n := by
-      -- Porting note: Original proof was `by linarith only [h, a.monotone hi]`
-      have := a.monotone hi
-      simp only at this ⊢
-      linarith only [h, this]
+    have h1 : a i + a (Fin.last m - k) ≤ n := by linarith only [h, a.monotone hi]
     have h2 : a i + a (Fin.last m - k) ∈ A := hadd _ (ha _) _ (ha _) h1
     rw [← mem_coe, ← range_orderEmbOfFin A hm, Set.mem_range] at h2
     cases' h2 with j hj

• depends on: #5966

Co-authored-by: Eric Wieser <wieser.eric@gmail.com> Co-authored-by: Scott Morrison <scott.morrison@gmail.com>

@@ -2,11 +2,6 @@
 Copyright (c) 2021 Antoine Labelle. All rights reserved.
 Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Antoine Labelle
-
-! This file was ported from Lean 3 source module imo.imo1994_q1
-! leanprover-community/mathlib commit 308826471968962c6b59c7ff82a22757386603e3
-! Please do not edit these lines, except to modify the commit id
-! if you have ported upstream changes.
 -/
 import Mathlib.Algebra.BigOperators.Basic
 import Mathlib.Algebra.BigOperators.Order
@@ -16,6 +11,8 @@ import Mathlib.Data.Fin.Interval
 import Mathlib.Tactic.Linarith
 import Mathlib.Tactic.ByContra
 
+#align_import imo.imo1994_q1 from "leanprover-community/mathlib"@"308826471968962c6b59c7ff82a22757386603e3"
+
 /-!
 # IMO 1994 Q1