K–theory of co-existentially closed continua

by CHRISTOPHER J. EAGLE JOSHUA LAU

discusses algebraically closed fields.

We prove that there is a complex number z with z^2 + 2 = 0.

theorem algClosExa₁ : ∃ (z : ℂ), z ^ 2 + 1 = 0

theorem algClosExa₂ : ∃ (z : ℂ), z ^ 2 + 2 = 0