English
A basic algebraic identity about negation and multiplication used in manipulation of series.
Русский
Базовая алгебраическая тождественность относительно отрицания и умножения, применяемая в работе с рядами.
LaTeX
$$$-(a\\,b) = a(-b)$$$
Lean4
/-- **Dirichlet's Theorem** on primes in arithmetic progression: if `q` is a positive
integer and `a : ZMod q` is a unit, then there are infinitely many prime numbers `p`
such that `(p : ZMod q) = a`. -/
theorem setOf_prime_and_eq_mod_infinite (ha : IsUnit a) : {p : ℕ | p.Prime ∧ (p : ZMod q) = a}.Infinite :=
by
by_contra H
rw [Set.not_infinite] at H
exact not_summable_residueClass_prime_div ha <| summable_of_finite_support <| support_residueClass_prime_div a ▸ H