English
The identity relation is the graph of the identity function: idRel = { p ∈ α×α | p1 = p2 }.
Русский
Идентичное отношение есть график функции тождественного отображения: idRel = { p ∈ α×α | p1 = p2 }.
LaTeX
$$$\\mathrm{idRel} := \\{ p \\in \\alpha \\times \\alpha \\mid p_{1} = p_{2} \\}$$$
Lean4
/-- The identity relation, or the graph of the identity function -/
def idRel {α : Type*} :=
{p : α × α | p.1 = p.2}