English
If α is a finite group of prime order p, then α is simple.
Русский
Если группа α конечна и имеет порядок p, где p простое, то она простая.
LaTeX
$$IsSimpleGroup α$$
Lean4
/-- A finite group of prime order is simple. -/
@[to_additive /-- A finite group of prime order is simple. -/
]
theorem isSimpleGroup_of_prime_card {p : ℕ} [hp : Fact p.Prime] (h : Nat.card α = p) : IsSimpleGroup α :=
by
subst h
have : Finite α := Nat.finite_of_card_ne_zero hp.1.ne_zero
have : Nontrivial α := Finite.one_lt_card_iff_nontrivial.mp hp.1.one_lt
exact ⟨fun H _ => H.eq_bot_or_eq_top_of_prime_card⟩