mathlib-initiative/mathlib-tactics huggingface dataset:
Module: Mathlib.Order.ModularLattice

Goal state before:
pp: α : Type u_1
inst✝¹ : Lattice α
inst✝ : IsModularLattice α
x y z a b : α
⊢ Icc a (b ⊔ a) = Icc a (a ⊔ b)

Tactic:
rw [sup_comm]

Goal state after:
Module: Mathlib.Order.ModularLattice

Goal state before:
pp: α : Type u_1
inst✝¹ : Lattice α
inst✝ : IsModularLattice α
x y z a b : α
⊢ Ioo a (b ⊔ a) = Ioo a (a ⊔ b)

Tactic:
rw [sup_comm]

Goal state after:
Module: Mathlib.LinearAlgebra.Span.Defs

Goal state before:
pp: R : Type u_1
M : Type u_4
inst✝² : Semiring R
inst✝¹ : AddCommMonoid M
inst✝ : Module R M
s : Submodule R M
f : R →ₗ[R] ↥s
hf : Surjective ⇑f
x : M
hx : x ∈ s
⊢ ∃ a, a • ↑(f 1) = x

Tactic:
have ⟨r, eq⟩ := hf ⟨x, hx⟩

Goal state after:
R : Type u_1
M : Type u_4
inst✝² : Semiring R
inst✝¹ : AddCommMonoid M
inst✝ : Module R M
s : Submodule R M
f : R →ₗ[R] ↥s
hf : Surjective ⇑f
x : M
hx : x ∈ s
r : R
eq : f r = ⟨x, hx⟩
⊢ ∃ a, a • ↑(f 1) = x
Module: Mathlib.LinearAlgebra.Span.Defs

Goal state before:
pp: R : Type u_1
M : Type u_4
inst✝³ : Ring R
inst✝² : AddCommGroup M
inst✝¹ : Module R M
ι : Type u_8
inst✝ : DecidableEq ι
i j : ι
hij : i ≠ j
v : ι → M
r : R
⊢ span R (range (update v j (v j + r • v i))) = span R (range v)

Tactic:
refine le_antisymm ?_ ?_ <;> simp only [span_le, Set.range_subset_iff, SetLike.mem_coe]

Goal state after:
case refine_1
R : Type u_1
M : Type u_4
inst✝³ : Ring R
inst✝² : AddCommGroup M
inst✝¹ : Module R M
ι : Type u_8
inst✝ : DecidableEq ι
i j : ι
hij : i ≠ j
v : ι → M
r : R
⊢ ∀ (y : ι), update v j (v j + r • v i) y ∈ span R (range v)

case refine_2
R : Type u_1
M : Type u_4
inst✝³ : Ring R
inst✝² : AddCommGroup M
inst✝¹ : Module R M
ι : Type u_8
inst✝ : DecidableEq ι
i j : ι
hij : i ≠ j
v : ι → M
r : R
⊢ ∀ (y : ι), v y ∈ span R (range (update v j (v j + r • v i)))
Module: Mathlib.LinearAlgebra.Span.Defs

Goal state before:
pp: case refine_1.inl
R : Type u_1
M : Type u_4
inst✝³ : Ring R
inst✝² : AddCommGroup M
inst✝¹ : Module R M
ι : Type u_8
inst✝ : DecidableEq ι
i j : ι
hij : i ≠ j
v : ι → M
r : R
⊢ update v j (v j + r • v i) j ∈ span R (range v)

Tactic:
update_self

Goal state after:
case refine_1.inl
R : Type u_1
M : Type u_4
inst✝³ : Ring R
inst✝² : AddCommGroup M
inst✝¹ : Module R M
ι : Type u_8
inst✝ : DecidableEq ι
i j : ι
hij : i ≠ j
v : ι → M
r : R
⊢ v j + r • v i ∈ span R (range v)
Module: Mathlib.Order.SupIndep

Goal state before:
pp: α : Type u_1
ι : Type u_3
inst✝¹ : CompleteLattice α
inst✝ : IsModularLattice α
f g : ι → α
h₁ : iSupIndep g
h₂ : iSup f = ⊤
⊢ f ≤ g ↔ f = g

Tactic:
refine ⟨fun h₃ ↦ funext fun i ↦ ?_, le_of_eq⟩
  replace h₁ : Disjoint (⨆ (j) (_ : j ≠ i), f j) (g i) :=
    Disjoint.mono_left (iSup₂_mono fun j _ ↦ h₃ j) (h₁ i).symm
  replace h₂ : Codisjoint (f i) (⨆ (j) (_ : j ≠ i), f j) := by
    rw [codisjoint_iff, ← iSup_split_single f i, h₂]
  exact (le_iff_eq_of_codisjoint_of_disjoint h₂ h₁).mp (h₃ i)

Goal state after:
Module: Mathlib.Algebra.Algebra.Tower

Goal state before:
pp: R : Type u
S : Type v
A : Type w
inst✝⁶ : Semiring R
inst✝⁵ : Semiring S
inst✝⁴ : AddCommMonoid A
inst✝³ : Module R S
inst✝² : Module S A
inst✝¹ : Module R A
inst✝ : IsScalarTower R S A
s : Set S
t : Set A
k : S
hks : k ∈ span R s
x : A
hx : x ∈ t
c₁ c₂ : S
x✝¹ : c₁ ∈ span R s
x✝ : c₂ ∈ span R s
ih₁ : c₁ • x ∈ span R (s • t)
ih₂ : c₂ • x ∈ span R (s • t)
⊢ (c₁ + c₂) • x ∈ span R (s • t)

Tactic:
rw [add_smul]

Goal state after:
R : Type u
S : Type v
A : Type w
inst✝⁶ : Semiring R
inst✝⁵ : Semiring S
inst✝⁴ : AddCommMonoid A
inst✝³ : Module R S
inst✝² : Module S A
inst✝¹ : Module R A
inst✝ : IsScalarTower R S A
s : Set S
t : Set A
k : S
hks : k ∈ span R s
x : A
hx : x ∈ t
c₁ c₂ : S
x✝¹ : c₁ ∈ span R s
x✝ : c₂ ∈ span R s
ih₁ : c₁ • x ∈ span R (s • t)
ih₂ : c₂ • x ∈ span R (s • t)
⊢ c₁ • x + c₂ • x ∈ span R (s • t)
Module: Mathlib.Algebra.Algebra.Tower

Goal state before:
pp: case refine_2
R : Type u
S : Type v
A : Type w
inst✝⁶ : Semiring R
inst✝⁵ : Semiring S
inst✝⁴ : AddCommMonoid A
inst✝³ : Module R S
inst✝² : Module S A
inst✝¹ : Module R A
inst✝ : IsScalarTower R S A
s : Set S
hs : span R s = ⊤
t : Set A
x✝¹ : A
hp : x✝¹ ∈ restrictScalars R (span S t)
s0 : S
y : A
hy : y ∈ t
x✝ y✝ : S
hx✝ : x✝ ∈ span R s
hy✝ : y✝ ∈ span R s
⊢ x✝ • y ∈ span R (s • t) → y✝ • y ∈ span R (s • t) → (x✝ + y✝) • y ∈ span R (s • t)

Tactic:
rw [add_smul]

Goal state after:
case refine_2
R : Type u
S : Type v
A : Type w
inst✝⁶ : Semiring R
inst✝⁵ : Semiring S
inst✝⁴ : AddCommMonoid A
inst✝³ : Module R S
inst✝² : Module S A
inst✝¹ : Module R A
inst✝ : IsScalarTower R S A
s : Set S
hs : span R s = ⊤
t : Set A
x✝¹ : A
hp : x✝¹ ∈ restrictScalars R (span S t)
s0 : S
y : A
hy : y ∈ t
x✝ y✝ : S
hx✝ : x✝ ∈ span R s
hy✝ : y✝ ∈ span R s
⊢ x✝ • y ∈ span R (s • t) → y✝ • y ∈ span R (s • t) → x✝ • y + y✝ • y ∈ span R (s • t)
Module: Mathlib.LinearAlgebra.Span.Basic

Goal state before:
pp: R : Type u_1
M : Type u_4
S : Type u_7
inst✝⁶ : Semiring R
inst✝⁵ : AddCommMonoid M
inst✝⁴ : Module R M
inst✝³ : Semiring S
inst✝² : SMul R S
inst✝¹ : Module S M
inst✝ : IsScalarTower R S M
p : Submodule R M
x y : ↥p
hxy : ↑((inclusionSpan S p) x) = ↑((inclusionSpan S p) y)
⊢ x = y

Tactic:
simpa using hxy

Goal state after:
Module: Mathlib.Order.CompactlyGenerated.Basic

Goal state before:
pp: α : Type u_2
inst✝¹ : CompleteLattice α
inst✝ : IsCompactlyGenerated α
ι : Type u_3
f : ι → α
s : Set ι
a : α
hs : ∀ t ⊆ s, t.Finite → Disjoint (⨆ i ∈ t, f i) a
⊢ (⨆ i ∈ s, f i) ⊓ a = ⊥

Tactic:
iSup_subtype',

Goal state after:
α : Type u_2
inst✝¹ : CompleteLattice α
inst✝ : IsCompactlyGenerated α
ι : Type u_3
f : ι → α
s : Set ι
a : α
hs : ∀ t ⊆ s, t.Finite → Disjoint (⨆ i ∈ t, f i) a
⊢ (⨆ x, f ↑x) ⊓ a = ⊥
Module: Mathlib.Algebra.BigOperators.Pi

Goal state before:
pp: ι✝ : Type u_1
κ : Type u_2
M✝ : Type u_3
N : Type u_4
R : Type u_5
α : Type u_6
ι : Type u_7
inst✝³ : Fintype ι
inst✝² : DecidableEq ι
M : ι → Type u_8
inst✝¹ : (i : ι) → CommMonoid (M i)
M' : Type u_9
inst✝ : CommMonoid M'
φ : (i : ι) → M i →* M'
i : ι
m : M i
φ' : (i : ι) → M i → M' := fun i ↦ ⇑(φ i)
| ∏ x, (φ x) (mulSingle i m x) = (φ i) m

Tactic:
enter [

Goal state after:
ι✝ : Type u_1
κ : Type u_2
M✝ : Type u_3
N : Type u_4
R : Type u_5
α : Type u_6
ι : Type u_7
inst✝³ : Fintype ι
inst✝² : DecidableEq ι
M : ι → Type u_8
inst✝¹ : (i : ι) → CommMonoid (M i)
M' : Type u_9
inst✝ : CommMonoid M'
φ : (i : ι) → M i →* M'
i : ι
m : M i
φ' : (i : ι) → M i → M' := fun i ↦ ⇑(φ i)
| ∏ x, (φ x) (mulSingle i m x) = (φ i) m
Module: Mathlib.Data.List.Find

Goal state before:
pp: case swap
α : Type u_1
p : α → Bool
l₁ l₂ : List α
x y : α
l : List α
hp : {x_1 | x_1 ∈ y :: x :: l ∧ p x_1 = true}.Subsingleton
⊢ find? p (y :: x :: l) = find? p (x :: y :: l)

Tactic:
dsimp [Set.Subsingleton] at hp
    by_cases p x <;> by_cases p y <;> grind

Goal state after:
Module: Mathlib.Data.Multiset.Find

Goal state before:
pp: α : Type u_1
p₁ p₂ : α → Prop
inst✝¹ : DecidablePred p₁
inst✝ : DecidablePred p₂
s : Multiset α
hp₁ : {x | x ∈ s ∧ p₁ x}.Subsingleton
h : ∀ (x : α), x ∈ s → (p₁ x ↔ p₂ x)
⊢ find? p₁ s hp₁ = find? p₂ s ⋯

Tactic:
induction s using Quotient.ind
  exact List.find?_congr fun x hx ↦ by simp [h x (by simpa using hx)]

Goal state after:
Module: Mathlib.Data.Finsupp.Defs

Goal state before:
pp: α : Type u_1
M : Type u_4
inst✝ : Zero M
s : Finset α
f : α → M
hf : ∀ (a : α), f a ≠ 0 → a ∈ s
a : α
⊢ a ∈ (onFinset s f hf).support ↔ f a ≠ 0

Tactic:
rw [Finsupp.mem_support_iff, Finsupp.onFinset_apply]

Goal state after:
Module: Mathlib.LinearAlgebra.Span.Basic

Goal state before:
pp: R : Type u_1
inst✝ : Semiring R
e : R
h : ∀ (x : R), x * (e * e) = x * e
⊢ e * e = e

Tactic:
conv_rhs => rw [← one_mul e, ← h, one_mul]

Goal state after:
Module: Mathlib.LinearAlgebra.Span.Basic

Goal state before:
pp: R : Type u_1
inst✝ : Semiring R
e : R
h : ∀ (x : R), x * (e * e) = x * e
⊢ e * e = e

Tactic:
by conv_rhs => rw [← one_mul e, ← h, one_mul]

Goal state after:
Module: Mathlib.Algebra.Group.Finsupp

Goal state before:
pp: ι : Type u_1
M : Type u_3
inst✝ : AddZeroClass M
a : ι
f : ι →₀ M
⊢ f.update a (f a) = f

Tactic:
update_self

Goal state after:
ι : Type u_1
M : Type u_3
inst✝ : AddZeroClass M
a : ι
f : ι →₀ M
⊢ f = f
Module: Mathlib.Algebra.Order.Group.Indicator

Goal state before:
pp: ι : Sort u_1
α : Type u_2
M : Type u_3
inst✝² : CompleteLattice M
inst✝¹ : One M
inst✝ : Nonempty ι
h1 : ⊥ = 1
s : ι → Set α
f : α → M
x : α
j : ι
hj : x ∉ s j
⊢ 1 ≤ ⨅ i, (s i).mulIndicator f x

Tactic:
by simp only [← h1, le_iInf_iff, bot_le, forall_const]

Goal state after:
Module: Mathlib.Algebra.GroupWithZero.Indicator

Goal state before:
pp: ι : Type u_1
M₀ : Type u_4
inst✝¹ : MonoidWithZero M₀
inst✝ : IsReduced M₀
n : ℕ
f : ι → M₀
hn : n ≠ 0
x✝ : ι
⊢ (x✝ ∈ support fun a ↦ f a ^ n) ↔ x✝ ∈ support f

Tactic:
exact (pow_eq_zero_iff hn).not

Goal state after:
Module: Mathlib.Data.Finsupp.Basic

Goal state before:
pp: α : Type u_12
M : Type u_13
inst✝ : Zero M
f g : α →₀ M
h : f.graph = g.graph
⊢ f = g

Tactic:
classical
    have hsup : f.support = g.support := by rw [← image_fst_graph, h, image_fst_graph]
    refine ext_iff'.2 ⟨hsup, fun x hx => apply_eq_of_mem_graph <| h.symm ▸ ?_⟩
    exact mk_mem_graph _ (hsup ▸ hx)

Goal state after:
Module: Mathlib.Data.Finsupp.Basic

Goal state before:
pp: case h₀
α : Type u_1
β : Type u_2
M : Type u_5
inst✝ : AddCommMonoid M
f : α → β
hf : Injective f
x : α →₀ M
a b : α
a✝ : x b ≠ 0
hba : b ≠ a
⊢ (single (f b) (x b)) (f a) = 0

Tactic:
exact single_eq_of_ne' (hf.ne hba)

Goal state after:
Module: Mathlib.Data.Finsupp.Basic

Goal state before:
pp: α : Type u_1
β : Type u_2
M : Type u_5
inst✝ : AddCommMonoid M
f : α → β
x : α →₀ M
a : β
h : a ∉ Set.range f
⊢ a ∉ f '' ↑x.support

Tactic:
by grw [Set.image_subset_range]; exact h

Goal state after:
Module: Mathlib.Data.Finsupp.Basic

Goal state before:
pp: α : Type u_1
β : Type u_2
M : Type u_5
inst✝ : Zero M
f : α → β
l : β →₀ M
hf : Set.BijOn f (f ⁻¹' ↑l.support) ↑l.support
⊢ { support := l.support.preimage f ⋯, toFun := fun a ↦ l (f a), mem_support_toFun := ⋯ }.support = ∅ → l.support = ∅

Tactic:
simp_rw [Finset.ext_iff, Finset.notMem_empty, iff_false, mem_preimage]

Goal state after:
α : Type u_1
β : Type u_2
M : Type u_5
inst✝ : Zero M
f : α → β
l : β →₀ M
hf : Set.BijOn f (f ⁻¹' ↑l.support) ↑l.support
⊢ (∀ (a : α), f a ∉ l.support) → ∀ (a : β), a ∉ l.support
Module: Mathlib.Data.Finsupp.Basic

Goal state before:
pp: case e'_1.e'_4
α : Type u_1
β : Type u_2
M : Type u_5
inst✝ : AddCommMonoid M
f : α ↪ β
x : β →₀ M
⊢ embDomain f = mapDomain ⇑f

pp: case e'_2
α : Type u_1
β : Type u_2
M : Type u_5
inst✝ : AddCommMonoid M
f : α ↪ β
x : β →₀ M
⊢ ↑x.support ⊆ Set.range ⇑f ↔ ∀ b ∉ Set.range ⇑f, x b = 0

Tactic:
· ext; rw [embDomain_eq_mapDomain]

Goal state after:
case e'_2
α : Type u_1
β : Type u_2
M : Type u_5
inst✝ : AddCommMonoid M
f : α ↪ β
x : β →₀ M
⊢ ↑x.support ⊆ Set.range ⇑f ↔ ∀ b ∉ Set.range ⇑f, x b = 0
Module: Mathlib.Algebra.Order.BigOperators.Group.Finset

Goal state before:
pp: ι : Type u_1
M : Type u_4
inst✝² : CommMonoid M
inst✝¹ : LinearOrder M
s : Finset ι
inst✝ : IsOrderedCancelMonoid M
f : ι → M
h₁ : ∀ i ∈ s, f i ≤ 1
i : ι
m : i ∈ s
i_ne : f i ≠ 1
⊢ ∏ i ∈ s, f i ≠ 1

Tactic:
apply ne_of_lt

Goal state after:
ι : Type u_1
M : Type u_4
inst✝² : CommMonoid M
inst✝¹ : LinearOrder M
s : Finset ι
inst✝ : IsOrderedCancelMonoid M
f : ι → M
h₁ : ∀ i ∈ s, f i ≤ 1
i : ι
m : i ∈ s
i_ne : f i ≠ 1
⊢ ∏ i ∈ s, f i < 1
Module: Mathlib.LinearAlgebra.Finsupp.Supported

Goal state before:
pp: α : Type u_1
M : Type u_2
N : Type u_3
P : Type u_4
R : Type u_5
S : Type u_6
inst✝⁷ : Semiring R
inst✝⁶ : Semiring S
inst✝⁵ : AddCommMonoid M
inst✝⁴ : Module R M
inst✝³ : AddCommMonoid N
inst✝² : Module R N
inst✝¹ : AddCommMonoid P
inst✝ : Module R P
s : Set α
p q : α →₀ M
hp : p ∈ {p | ↑p.support ⊆ s}
hq : q ∈ {p | ↑p.support ⊆ s}
⊢ p + q ∈ {p | ↑p.support ⊆ s}

Tactic:
refine Subset.trans (Subset.trans (Finset.coe_subset.2 support_add) ?_) (union_subset hp hq)
    rw [Finset.coe_union]

Goal state after:
Module: Mathlib.LinearAlgebra.Finsupp.LinearCombination

Goal state before:
pp: case mp
α : Type u_1
M : Type u_2
R : Type u_5
inst✝² : Semiring R
inst✝¹ : AddCommMonoid M
inst✝ : Module R M
v : α → M
x : M
hx : ∃ y, (linearCombination R v) y = x
⊢ x ∈ span R (Set.range v)

Tactic:
rcases hx with ⟨l, hl⟩

Goal state after:
case mp
α : Type u_1
M : Type u_2
R : Type u_5
inst✝² : Semiring R
inst✝¹ : AddCommMonoid M
inst✝ : Module R M
v : α → M
x : M
l : α →₀ R
hl : (linearCombination R v) l = x
⊢ x ∈ span R (Set.range v)
Module: Mathlib.LinearAlgebra.Basis.Defs

Goal state before:
pp: ι : Type u_1
ι' : Type u_2
R : Type u_3
M : Type u_6
inst✝² : Semiring R
inst✝¹ : AddCommMonoid M
inst✝ : Module R M
b : Basis ι R M
e : ι ≃ ι'
⊢ range ⇑(b.reindex e) = range ⇑b

Tactic:
simp [coe_reindex, range_comp]

Goal state after:
Module: Mathlib.Data.Fintype.Fin

Goal state before:
pp: case cons
α : Type u_1
n✝ : ℕ
inst✝ : DecidableEq α
a : α
n : ℕ
x : α
xs : List.Vector α n
hxs : #{i | xs.get i = a} = List.count a xs.toList
⊢ (if x = a then 1 else 0) + #{x_1 | (x ::ᵥ xs).get x_1.succ = a} = List.count a (x :: xs.toList)

Tactic:
Vector.get_cons_succ,

Goal state after:
case cons
α : Type u_1
n✝ : ℕ
inst✝ : DecidableEq α
a : α
n : ℕ
x : α
xs : List.Vector α n
hxs : #{i | xs.get i = a} = List.count a xs.toList
⊢ (if x = a then 1 else 0) + #{x | xs.get x = a} = List.count a (x :: xs.toList)
Module: Mathlib.Algebra.BigOperators.Finprod

Goal state before:
pp: α : Type u_1
β : Type u_2
M : Type u_5
inst✝ : CommMonoid M
f : α → M
s : Set β
g : β → α
hg : InjOn g (s ∩ mulSupport (f ∘ g))
⊢ ∏ᶠ (i : α) (_ : i ∈ g '' s), f i = ∏ᶠ (j : β) (_ : j ∈ s), f (g j)

Tactic:
by_cases hs : (s ∩ mulSupport (f ∘ g)).Finite

Goal state after:
case pos
α : Type u_1
β : Type u_2
M : Type u_5
inst✝ : CommMonoid M
f : α → M
s : Set β
g : β → α
hg : InjOn g (s ∩ mulSupport (f ∘ g))
hs : (s ∩ mulSupport (f ∘ g)).Finite
⊢ ∏ᶠ (i : α) (_ : i ∈ g '' s), f i = ∏ᶠ (j : β) (_ : j ∈ s), f (g j)

case neg
α : Type u_1
β : Type u_2
M : Type u_5
inst✝ : CommMonoid M
f : α → M
s : Set β
g : β → α
hg : InjOn g (s ∩ mulSupport (f ∘ g))
hs : ¬(s ∩ mulSupport (f ∘ g)).Finite
⊢ ∏ᶠ (i : α) (_ : i ∈ g '' s), f i = ∏ᶠ (j : β) (_ : j ∈ s), f (g j)
Module: Mathlib.Algebra.BigOperators.Finprod

Goal state before:
pp: α : Type u_1
M : Type u_5
inst✝ : CommMonoid M
f : Option α → M
hf : HasFiniteMulSupport (f ∘ some)
⊢ (mulSupport f).Finite

Tactic:
simpa [finite_option]

Goal state after:
Module: Mathlib.Data.ENat.Pow

Goal state before:
pp: y : ℕ∞
⊢ 1 ^ y = 1

Tactic:
induction y with
  | top => rfl
  | coe y => rw [epow_natCast, one_pow]

Goal state after:
Module: Mathlib.LinearAlgebra.LinearIndependent.Defs

Goal state before:
pp: ι : Type u'
R : Type u_2
M : Type u_4
v : ι → M
inst✝² : Semiring R
inst✝¹ : AddCommMonoid M
inst✝ : Module R M
hv : ∀ (l₁ l₂ : ι →₀ R), (Finsupp.linearCombination R v) l₁ = (Finsupp.linearCombination R v) l₂ → l₁ = l₂
s : Finset ι
f g : ι → R
eq : ∑ i ∈ s, f i • v i = ∑ i ∈ s, g i • v i
i : ι
his : i ∈ s
h : ∑ i ∈ s, Finsupp.single i (f i) = ∑ i ∈ s, Finsupp.single i (g i)
this : ∀ (f : ι → R), f i = (∑ j ∈ s, Finsupp.single j (f j)) i
⊢ f i = g i

Tactic:
rw [this f, this g, h]

Goal state after:
Module: Mathlib.Algebra.Group.ModEq

Goal state before:
pp: G : Type u_1
inst✝ : AddCommGroup G
p a b : G
⊢ (∃ m, b - a = m • p) ↔ ∃ z, b = a + z • p

Tactic:
sub_eq_iff_eq_add'

Goal state after:
Module: Mathlib.Data.Nat.ModEq

Goal state before:
pp: m a b c : ℕ
hm : 0 < m
h : c * a ≡ c * b [MOD m]
d : ℕ := m.gcd c
hmd : m.gcd c ∣ m
hcd : m.gcd c ∣ c
⊢ a ≡ b [MOD m / m.gcd c]

Tactic:
rw [modEq_iff_dvd]

Goal state after:
m a b c : ℕ
hm : 0 < m
h : c * a ≡ c * b [MOD m]
d : ℕ := m.gcd c
hmd : m.gcd c ∣ m
hcd : m.gcd c ∣ c
⊢ ↑(m / m.gcd c) ∣ ↑b - ↑a
Module: Mathlib.Algebra.BigOperators.Fin

Goal state before:
pp: case succ
ι : Type u_1
M : Type u_2
m n : ℕ
a : Fin (m ^ (n + 1))
ih : ∀ i < m ^ n, ∑ x, i / m ^ ↑x % m * m ^ ↑x = i
⊢ ↑a % m + ∑ x, ↑a / m / m ^ ↑x % m * (m * m ^ ↑x) = ↑a

Tactic:
mul_left_comm _ m,

Goal state after:
case succ
ι : Type u_1
M : Type u_2
m n : ℕ
a : Fin (m ^ (n + 1))
ih : ∀ i < m ^ n, ∑ x, i / m ^ ↑x % m * m ^ ↑x = i
⊢ ↑a % m + ∑ x, m * (↑a / m / m ^ ↑x % m * m ^ ↑x) = ↑a
Module: Mathlib.Data.Nat.ModEq

Goal state before:
pp: case neg
a b c : ℕ
h : ¬c = 0
⊢ (a + b) / c ≤ a / c + b / c + 1

Tactic:
rw [Nat.add_div (Nat.pos_of_ne_zero h), Nat.add_le_add_iff_left]
    split <;> decide

Goal state after:
Module: Mathlib.Data.ZMod.Defs

Goal state before:
pp: n : ℕ
x✝² x✝¹ x✝ : Fin n
a : ℕ
isLt✝² : a < n
b : ℕ
isLt✝¹ : b < n
c : ℕ
isLt✝ : c < n
⊢ a * (b + c) ≡ a * b + a * c [MOD n]

Tactic:
mul_add

Goal state after:
n : ℕ
x✝² x✝¹ x✝ : Fin n
a : ℕ
isLt✝² : a < n
b : ℕ
isLt✝¹ : b < n
c : ℕ
isLt✝ : c < n
⊢ a * b + a * c ≡ a * b + a * c [MOD n]
Module: Mathlib.LinearAlgebra.LinearIndependent.Defs

Goal state before:
pp: ι : Type u'
R : Type u_2
M : Type u_4
v : ι → M
inst✝⁸ : Semiring R
inst✝⁷ : AddCommMonoid M
inst✝⁶ : Module R M
inst✝⁵ : LinearOrder R
inst✝⁴ : CanonicallyOrderedAdd R
inst✝³ : AddRightReflectLE R
inst✝² : IsCancelAdd M
inst✝¹ : DecidableEq ι
inst✝ : Fintype ι
⊢ (∀ (s t : Finset ι) (f : ι → R),
      Disjoint s t → ∑ i ∈ s, f i • v i = ∑ i ∈ t, f i • v i → (∀ i ∈ s, f i = 0) ∧ ∀ i ∈ t, f i = 0) ↔
    ∀ (t : Finset ι) (f : ι → R), ∑ i ∈ t, f i • v i = ∑ i ∈ tᶜ, f i • v i → ∀ (i : ι), f i = 0

Tactic:
refine ⟨fun h t f heq i => ?_, fun h t₁ t₂ f ht₁t₂ heq => ?_⟩

Goal state after:
case refine_1
ι : Type u'
R : Type u_2
M : Type u_4
v : ι → M
inst✝⁸ : Semiring R
inst✝⁷ : AddCommMonoid M
inst✝⁶ : Module R M
inst✝⁵ : LinearOrder R
inst✝⁴ : CanonicallyOrderedAdd R
inst✝³ : AddRightReflectLE R
inst✝² : IsCancelAdd M
inst✝¹ : DecidableEq ι
inst✝ : Fintype ι
h :
  ∀ (s t : Finset ι) (f : ι → R),
    Disjoint s t → ∑ i ∈ s, f i • v i = ∑ i ∈ t, f i • v i → (∀ i ∈ s, f i = 0) ∧ ∀ i ∈ t, f i = 0
t : Finset ι
f : ι → R
heq : ∑ i ∈ t, f i • v i = ∑ i ∈ tᶜ, f i • v i
i : ι
⊢ f i = 0

case refine_2
ι : Type u'
R : Type u_2
M : Type u_4
v : ι → M
inst✝⁸ : Semiring R
inst✝⁷ : AddCommMonoid M
inst✝⁶ : Module R M
inst✝⁵ : LinearOrder R
inst✝⁴ : CanonicallyOrderedAdd R
inst✝³ : AddRightReflectLE R
inst✝² : IsCancelAdd M
inst✝¹ : DecidableEq ι
inst✝ : Fintype ι
h : ∀ (t : Finset ι) (f : ι → R), ∑ i ∈ t, f i • v i = ∑ i ∈ tᶜ, f i • v i → ∀ (i : ι), f i = 0
t₁ t₂ : Finset ι
f : ι → R
ht₁t₂ : Disjoint t₁ t₂
heq : ∑ i ∈ t₁, f i • v i = ∑ i ∈ t₂, f i • v i
⊢ (∀ i ∈ t₁, f i = 0) ∧ ∀ i ∈ t₂, f i = 0
Module: Mathlib.LinearAlgebra.LinearIndependent.Basic

Goal state before:
pp: case insert
G : Type u_6
inst✝² : MulOneClass G
L : Type u_7
inst✝¹ : CommRing L
inst✝ : IsDomain L
this✝ : DecidableEq (G →* L) := Classical.decEq (G →* L)
this : MulAction L L := Semiring.toModule.toMulAction
a : G →* L
s : Finset (G →* L)
has : a ∉ s
ih : ∀ (g : (G →* L) → L), ∑ i ∈ s, g i • ⇑i = 0 → ∀ i ∈ s, g i = 0
g : (G →* L) → L
hg : ∑ i ∈ insert a s, g i • ⇑i = 0
h1 : ∀ i ∈ s, g i • ⇑i = g i • ⇑a
⊢ ∀ i ∈ insert a s, g i = 0

Tactic:
have h2 (i) (his : i ∈ s) : ∃ y, i y ≠ a y := by
    by_contra! hia
    obtain rfl : i = a := MonoidHom.ext hia
    contradiction

Goal state after:
case insert
G : Type u_6
inst✝² : MulOneClass G
L : Type u_7
inst✝¹ : CommRing L
inst✝ : IsDomain L
this✝ : DecidableEq (G →* L) := Classical.decEq (G →* L)
this : MulAction L L := Semiring.toModule.toMulAction
a : G →* L
s : Finset (G →* L)
has : a ∉ s
ih : ∀ (g : (G →* L) → L), ∑ i ∈ s, g i • ⇑i = 0 → ∀ i ∈ s, g i = 0
g : (G →* L) → L
hg : ∑ i ∈ insert a s, g i • ⇑i = 0
h1 : ∀ i ∈ s, g i • ⇑i = g i • ⇑a
h2 : ∀ i ∈ s, ∃ y, i y ≠ a y
⊢ ∀ i ∈ insert a s, g i = 0
Module: Mathlib.LinearAlgebra.LinearIndependent.Defs

Goal state before:
pp: ι : Type u'
R : Type u_2
M : Type u_4
v : ι → M
inst✝⁷ : Semiring R
inst✝⁶ : AddCommMonoid M
inst✝⁵ : Module R M
inst✝⁴ : LinearOrder R
inst✝³ : CanonicallyOrderedAdd R
inst✝² : AddRightReflectLE R
inst✝¹ : IsCancelAdd M
inst✝ : DecidableEq ι
s : Finset ι
h : ∀ t ⊆ s, ∀ (f : ι → R), ∑ i ∈ t, f i • v i = ∑ i ∈ s \ t, f i • v i → ∀ i ∈ s, f i = 0
t : Finset ↑↑s
f : ↑↑s → R
heq : ∑ i ∈ t, f i • v ↑i = ∑ i ∈ tᶜ, f i • v ↑i
i : ↑↑s
| ∑ i ∈ Finset.map (Embedding.subtype fun x ↦ x ∈ ↑s) t, (if h : i ∈ s then f ⟨i, h⟩ else 0) • v i =
    ∑ i ∈ s \ Finset.map (Embedding.subtype fun x ↦ x ∈ ↑s) t, (if h : i ∈ s then f ⟨i, h⟩ else 0) • v i

Tactic:
enter [

Goal state after:
ι : Type u'
R : Type u_2
M : Type u_4
v : ι → M
inst✝⁷ : Semiring R
inst✝⁶ : AddCommMonoid M
inst✝⁵ : Module R M
inst✝⁴ : LinearOrder R
inst✝³ : CanonicallyOrderedAdd R
inst✝² : AddRightReflectLE R
inst✝¹ : IsCancelAdd M
inst✝ : DecidableEq ι
s : Finset ι
h : ∀ t ⊆ s, ∀ (f : ι → R), ∑ i ∈ t, f i • v i = ∑ i ∈ s \ t, f i • v i → ∀ i ∈ s, f i = 0
t : Finset ↑↑s
f : ↑↑s → R
heq : ∑ i ∈ t, f i • v ↑i = ∑ i ∈ tᶜ, f i • v ↑i
i : ↑↑s
| ∑ i ∈ Finset.map (Embedding.subtype fun x ↦ x ∈ ↑s) t, (if h : i ∈ s then f ⟨i, h⟩ else 0) • v i =
    ∑ i ∈ s \ Finset.map (Embedding.subtype fun x ↦ x ∈ ↑s) t, (if h : i ∈ s then f ⟨i, h⟩ else 0) • v i
Module: Mathlib.Data.Set.Card

Goal state before:
pp: α : Type u_1
s : Set α
⊢ s.encard = ⊤ ↔ s.Infinite

Tactic:
by
  contrapose!
  rw [← lt_top_iff_ne_top, encard_lt_top_iff]

Goal state after:
Module: Mathlib.Data.Set.Card

Goal state before:
pp: α : Type u_1
s : Set α
x : α
h : (insert x s).encard = 2
hx : x ∈ s
⊢ ∃ x y, x ≠ y ∧ s = {x, y}

Tactic:
← insert_sdiff_singleton,

Goal state after:
α : Type u_1
s : Set α
x : α
h : (insert x (s \ {x})).encard = 2
hx : x ∈ s
⊢ ∃ x y, x ≠ y ∧ s = {x, y}
Module: Mathlib.Data.Set.Card

Goal state before:
pp: case refine_1
α : Type u_1
s : Set α
x : α
h : (insert x s).encard = 3
hx : x ∈ s
⊢ ∃ x y z, x ≠ y ∧ x ≠ z ∧ y ≠ z ∧ s = {x, y, z}

Tactic:
← insert_sdiff_singleton,

Goal state after:
case refine_1
α : Type u_1
s : Set α
x : α
h : (insert x (s \ {x})).encard = 3
hx : x ∈ s
⊢ ∃ x y z, x ≠ y ∧ x ≠ z ∧ y ≠ z ∧ s = {x, y, z}
Module: Mathlib.Data.Set.Card

Goal state before:
pp: case refine_1
α : Type u_1
s : Set α
x : α
h : (insert x s).encard = 4
hx : x ∈ s
⊢ ∃ x y z w, x ≠ y ∧ x ≠ z ∧ x ≠ w ∧ y ≠ z ∧ y ≠ w ∧ z ≠ w ∧ s = {x, y, z, w}

Tactic:
← insert_sdiff_singleton,

Goal state after:
case refine_1
α : Type u_1
s : Set α
x : α
h : (insert x (s \ {x})).encard = 4
hx : x ∈ s
⊢ ∃ x y z w, x ≠ y ∧ x ≠ z ∧ x ≠ w ∧ y ≠ z ∧ y ≠ w ∧ z ≠ w ∧ s = {x, y, z, w}
Module: Mathlib.Data.Set.Card

Goal state before:
pp: case h
α : Type u_1
β : Type u_2
inst✝ : Nonempty β
s : Set α
t : Set β
hs : s.Finite
hle : s.encard ≤ t.encard
a : α
has : a ∈ s
b : β
hbt : b ∈ t
hle' : (s \ {a}).encard ≤ (t \ {b}).encard
f₀ : α → β
hinj : InjOn f₀ (s \ {a})
hf₀s : ∀ x ∈ s, ¬x = a → f₀ x ∈ t ∧ ¬f₀ x = b
⊢ insert a s ⊆ Function.update f₀ a b ⁻¹' t ∧ InjOn (Function.update f₀ a b) (insert a s)

Tactic:
← insert_sdiff_singleton,

Goal state after:
case h
α : Type u_1
β : Type u_2
inst✝ : Nonempty β
s : Set α
t : Set β
hs : s.Finite
hle : s.encard ≤ t.encard
a : α
has : a ∈ s
b : β
hbt : b ∈ t
hle' : (s \ {a}).encard ≤ (t \ {b}).encard
f₀ : α → β
hinj : InjOn f₀ (s \ {a})
hf₀s : ∀ x ∈ s, ¬x = a → f₀ x ∈ t ∧ ¬f₀ x = b
⊢ insert a (s \ {a}) ⊆ Function.update f₀ a b ⁻¹' t ∧ InjOn (Function.update f₀ a b) (insert a (s \ {a}))
Module: Mathlib.SetTheory.Cardinal.NatCard

Goal state before:
pp: α : Type u_1
inst✝ : Finite α
p : α → Prop
⊢ Nat.card { x // p x } ≤ Nat.card α

Tactic:
have := Fintype.ofFinite α
  simpa only [Nat.card_eq_fintype_card] using Fintype.card_subtype_le p

Goal state after: