(* GENERIC RELOCATION WITH PAIRS ********************************************)
inductive minuss: nat → relation (list2 nat nat) ≝
-| minuss_nil: ∀i. minuss i ⟠ ⟠
+| minuss_nil: ∀i. minuss i ⟠ ⟠
| minuss_lt : ∀des1,des2,d,e,i. i < d → minuss i des1 des2 →
minuss i ({d, e} @ des1) ({d - i, e} @ des2)
| minuss_ge : ∀des1,des2,d,e,i. d ≤ i → minuss (e + i) des1 des2 →
∃∃des0. i < d & des ▭ i ≡ des0 &
des2 = {d - i, e} @ des0.
#des1 #des2 #i * -des1 -des2 -i
-[ #i #d #e #des #H destruct
+[ #i #d #e #des #H destruct
| #des1 #des #d1 #e1 #i1 #Hid1 #Hdes #d2 #e2 #des2 #H destruct /3 width=3/
| #des1 #des #d1 #e1 #i1 #Hdi1 #Hdes #d2 #e2 #des2 #H destruct /3 width=1/
]
qed-.
lemma minuss_inv_cons1_lt: ∀des1,des2,d,e,i. {d, e} @ des1 ▭ i ≡ des2 →
- i < d →
+ i < d →
∃∃des. des1 ▭ i ≡ des & des2 = {d - i, e} @ des.
#des1 #des2 #d #e #i #H
elim (minuss_inv_cons1 … H) -H * /2 width=3/ #Hdi #_ #Hid