English
If there is a unique index set I, then OrthogonalIdempotents e is equivalent to IsIdempotentElem (e default).
Русский
Если множество индексов единственно, то OrthogonalIdempotents e эквивалентно IsIdempotentElem (e по умолчанию).
LaTeX
$$OrthogonalIdempotents e ↔ IsIdempotentElem (e default)$$
Lean4
theorem unique [Unique I] : OrthogonalIdempotents e ↔ IsIdempotentElem (e default) := by
simp only [orthogonalIdempotents_iff, Unique.forall_iff, Subsingleton.pairwise, and_true]