Theorem: NonUnitalSubsemiring.mem_iSup_of_directed
File: Mathlib/RingTheory/NonUnitalSubsemiring/Basic.lean

Proof steps:
state_before: R : Type u
S✝ : Type v
T : Type w
inst✝⁴ : NonUnitalNonAssocSemiring R
M : Subsemigroup R
inst✝³ : NonUnitalNonAssocSemiring S✝
inst✝² : NonUnitalNonAssocSemiring T
F : Type u_1
inst✝¹ : FunLike F R S✝
inst✝ : NonUnitalRingHomClass F R S✝
ι : Sort u_2
hι : Nonempty ι
S : ι → NonUnitalSubsemiring R
hS : Directed (fun x x_1 => x ≤ x_1) S
x : R
⊢ x ∈ ⨆ i, S i ↔ ∃ i, x ∈ S i
state_after: R : Type u
S✝ : Type v
T : Type w
inst✝⁴ : NonUnitalNonAssocSemiring R
M : Subsemigroup R
inst✝³ : NonUnitalNonAssocSemiring S✝
inst✝² : NonUnitalNonAssocSemiring T
F : Type u_1
inst✝¹ : FunLike F R S✝
inst✝ : NonUnitalRingHomClass F R S✝
ι : Sort u_2
hι : Nonempty ι
S : ι → NonUnitalSubsemiring R
hS : Directed (fun x x_1 => x ≤ x_1) S
x : R
⊢ x ∈ ⨆ i, S i → ∃ i, x ∈ S i
tactic: refine ⟨?_, fun ⟨i, hi⟩ ↦ le_iSup S i hi⟩
state_before: R : Type u
S✝ : Type v
T : Type w
inst✝⁴ : NonUnitalNonAssocSemiring R
M : Subsemigroup R
inst✝³ : NonUnitalNonAssocSemiring S✝
inst✝² : NonUnitalNonAssocSemiring T
F : Type u_1
inst✝¹ : FunLike F R S✝
inst✝ : NonUnitalRingHomClass F R S✝
ι : Sort u_2
hι : Nonempty ι
S : ι → NonUnitalSubsemiring R
hS : Directed (fun x x_1 => x ≤ x_1) S
x : R
⊢ x ∈ ⨆ i, S i → ∃ i, x ∈ S i
state_after: R : Type u
S✝ : Type v
T : Type w
inst✝⁴ : NonUnitalNonAssocSemiring R
M : Subsemigroup R
inst✝³ : NonUnitalNonAssocSemiring S✝
inst✝² : NonUnitalNonAssocSemiring T
F : Type u_1
inst✝¹ : FunLike F R S✝
inst✝ : NonUnitalRingHomClass F R S✝
ι : Sort u_2
hι : Nonempty ι
S : ι → NonUnitalSubsemiring R
hS : Directed (fun x x_1 => x ≤ x_1) S
x : R
U : NonUnitalSubsemiring R :=
  NonUnitalSubsemiring.mk' (⋃ i, ↑(S i)) (⨆ i, (S i).toSubsemigroup) ⋯ (⨆ i, (S i).toAddSubmonoid) ⋯
⊢ x ∈ ⨆ i, S i → ∃ i, x ∈ S i
tactic: let U : NonUnitalSubsemiring R :=
    NonUnitalSubsemiring.mk' (⋃ i, (S i : Set R))
      (⨆ i, (S i).toSubsemigroup) (Subsemigroup.coe_iSup_of_directed hS)
      (⨆ i, (S i).toAddSubmonoid) (AddSubmonoid.coe_iSup_of_directed hS)
state_before: R : Type u
S✝ : Type v
T : Type w
inst✝⁴ : NonUnitalNonAssocSemiring R
M : Subsemigroup R
inst✝³ : NonUnitalNonAssocSemiring S✝
inst✝² : NonUnitalNonAssocSemiring T
F : Type u_1
inst✝¹ : FunLike F R S✝
inst✝ : NonUnitalRingHomClass F R S✝
ι : Sort u_2
hι : Nonempty ι
S : ι → NonUnitalSubsemiring R
hS : Directed (fun x x_1 => x ≤ x_1) S
x : R
U : NonUnitalSubsemiring R :=
  NonUnitalSubsemiring.mk' (⋃ i, ↑(S i)) (⨆ i, (S i).toSubsemigroup) ⋯ (⨆ i, (S i).toAddSubmonoid) ⋯
⊢ x ∈ ⨆ i, S i → ∃ i, x ∈ S i
state_after: R : Type u
S✝ : Type v
T : Type w
inst✝⁴ : NonUnitalNonAssocSemiring R
M : Subsemigroup R
inst✝³ : NonUnitalNonAssocSemiring S✝
inst✝² : NonUnitalNonAssocSemiring T
F : Type u_1
inst✝¹ : FunLike F R S✝
inst✝ : NonUnitalRingHomClass F R S✝
ι : Sort u_2
hι : Nonempty ι
S : ι → NonUnitalSubsemiring R
hS : Directed (fun x x_1 => x ≤ x_1) S
x : R
U : NonUnitalSubsemiring R :=
  NonUnitalSubsemiring.mk' (⋃ i, ↑(S i)) (⨆ i, (S i).toSubsemigroup) ⋯ (⨆ i, (S i).toAddSubmonoid) ⋯
⊢ ⨆ i, S i ≤ U
tactic: suffices H : ⨆ i, S i ≤ U by simpa [U] using @H x
state_before: R : Type u
S✝ : Type v
T : Type w
inst✝⁴ : NonUnitalNonAssocSemiring R
M : Subsemigroup R
inst✝³ : NonUnitalNonAssocSemiring S✝
inst✝² : NonUnitalNonAssocSemiring T
F : Type u_1
inst✝¹ : FunLike F R S✝
inst✝ : NonUnitalRingHomClass F R S✝
ι : Sort u_2
hι : Nonempty ι
S : ι → NonUnitalSubsemiring R
hS : Directed (fun x x_1 => x ≤ x_1) S
x : R
U : NonUnitalSubsemiring R :=
  NonUnitalSubsemiring.mk' (⋃ i, ↑(S i)) (⨆ i, (S i).toSubsemigroup) ⋯ (⨆ i, (S i).toAddSubmonoid) ⋯
⊢ ⨆ i, S i ≤ U
state_after: no goals
tactic: exact iSup_le fun i x hx => Set.mem_iUnion.2 ⟨i, hx⟩