congr
case intro.refine'_2.inr
a : ℤ√(-3)
hcoprime : IsCoprime a.re a.im
heven : Even a.norm
u' : ℤ√(-3)
hu' : a = { re := 1, im := -1 } * u'
⊢ { re := 1, im := -1 }.norm * u'.norm = 4 * u'.norm
no goals