simp only [add_re, int_cast_re, mul_re, int_cast_im, MulZeroClass.zero_mul, tsub_zero]
a b c : ℤω
⊢ (↑a.x + ↑a.y * { re := -1 / 2, im := rt3 / 2 }).re = ↑a.x - ↑a.y / 2
a b c : ℤω
⊢ ↑a.x + ↑a.y * (-1 / 2) = ↑a.x - ↑a.y / 2