∀W2. ⇧[0, i + 1] V2 ≡ W2 → ⦃G, L⦄ ⊢ #i ➡* W2.
#G #L #K #V #V2 #i #HLK #H elim H -V2 [ /3 width=6 by cpr_cprs, cpr_delta/ ]
#V1 #V2 #_ #HV12 #IHV1 #W2 #HVW2
∀W2. ⇧[0, i + 1] V2 ≡ W2 → ⦃G, L⦄ ⊢ #i ➡* W2.
#G #L #K #V #V2 #i #HLK #H elim H -V2 [ /3 width=6 by cpr_cprs, cpr_delta/ ]
#V1 #V2 #_ #HV12 #IHV1 #W2 #HVW2
elim (cpr_inv_lref1 … HT2) -HT2 /2 width=1 by or_introl/
* /4 width=6 by cpr_cprs, ex3_3_intro, or_intror/
| * #K #V1 #T1 #HLK #HVT1 #HT1
elim (cpr_inv_lref1 … HT2) -HT2 /2 width=1 by or_introl/
* /4 width=6 by cpr_cprs, ex3_3_intro, or_intror/
| * #K #V1 #T1 #HLK #HVT1 #HT1
elim (cpr_inv_lift1 … HT2 … H0LK … HT1) -H0LK -T
/4 width=6 by cprs_strap1, ex3_3_intro, or_intror/
]
elim (cpr_inv_lift1 … HT2 … H0LK … HT1) -H0LK -T
/4 width=6 by cprs_strap1, ex3_3_intro, or_intror/
]