contrapose! hodd with heqtwomul
case neg.refine'_2
a x : ℤ
hodd : Odd x
h0' : x ≠ 0
c : ℤ := a % x
hc : c = a % x
H : ↑(natAbs x) ≤ 2 * (a % x)
ofNat_two : ↑2 = 2
hcnonneg : 0 ≤ a % x
this : a % x < abs x
⊢ ↑(natAbs x) ≠ 2 * (a % x)
case neg.refine'_2
a x : ℤ
h0' : x ≠ 0
c : ℤ := a % x
hc : c = a % x
H : ↑(natAbs x) ≤ 2 * (a % x)
ofNat_two : ↑2 = 2
hcnonneg : 0 ≤ a % x
this : a % x < abs x
heqtwomul : ↑(natAbs x) = 2 * (a % x)
⊢ ¬Odd x