theorem
proved
term proof
empty_has_no_self_recognition
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formal statement (Lean)
50theorem empty_has_no_self_recognition (X : Type*) (h : IsEmpty X) :
51 ¬(∃ (R : X → X → Prop), ∃ x, R x x) := by
proof body
Term-mode proof.
52 intro ⟨_, x, _⟩
53 exact h.elim x
54
55/-! ## Recognition Structure -/
56
57/-- A recognition structure on a type.
58
59This captures the minimal structure needed for "things to be recognized."
60-/