update in basic_2

[helm.git] / matita / matita / contribs / lambdadelta / apps_2 / etc / models / model.etc

lemma pippo: ∀M,v1,v2,d,i. [i⬐d] v1 ≐⦋M⦌ v2 → v1 ≐⦋M⦌ ↓[i,1] v2.
#M #v1 #v2 #d #i #H #j elim (lt_or_ge … j i) #Hij
[ >lower_lt // <(H j) >raise_lt //
| >lower_ge // <(H (j+1)) >raise_gt /2 width=1 by le_S_S/
]
qed-.