19 lines
600 B
Text
19 lines
600 B
Text
theorem {u} not_mem_empty1 {A : Type u} (x : A) : x ∉ (∅ : set A) :=
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assume h, h
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theorem {u} not_mem_empty2 {A : Type u} (x : A) : x ∉ ∅ := -- ERROR here
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assume h, h
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theorem {u} not_mem_empty3 {A : Type u} (x : A) : x ∉ (∅ : set A) :=
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assume h : x ∈ ∅, h
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theorem {u} not_mem_empty4 {A : Type u} (x : A) : x ∉ (∅ : set A) :=
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assume h : x ∈ (∅ : set A), h
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theorem {u} not_mem_empty5 {A : Type u} (x : A) : x ∉ (∅ : set A) :=
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begin intro h, exact h end
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open tactic
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theorem {u} not_mem_empty6 {A : Type u} (x : A) : x ∉ (∅ : set A) :=
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by do h ← intro `h, exact h
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