u✝ u : XgcdType
h : r u ≠ 0
⊢ (if x : r u = 0 then finish u else flip (reduce (step u))) = flip (reduce (step u))
u✝ u : XgcdType
h : r u ≠ 0
⊢ reduce u = flip (reduce (step u))
rw [reduce]
no goals
u✝ u : XgcdType
h : r u ≠ 0
⊢ (if x : r u = 0 then finish u else flip (reduce (step u))) = flip (reduce (step u))
exact if_neg h