dedup_cons' — Mathlib

English

Dedup of cons is given by the case analysis depending on whether a is in dedup l.

Русский

Дедуп конc имеет вид: если a в dedup l, то dedup l, иначе a :: dedup l.

LaTeX

$$$$ dedup (a :: l) = \\begin{cases} dedup l, & a \\in dedup l \\\\ a :: dedup l, & \\text{otherwise} \\end{cases}. $$$$

Lean4

theorem dedup_cons' (a : α) (l : List α) : dedup (a :: l) = if a ∈ dedup l then dedup l else a :: dedup l := by
  split <;> simp [dedup_cons_of_mem', dedup_cons_of_notMem', *]

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