Definition contiguous_range_exact_lo xs lo :=
    (forall i,
       lo < i <= maxIndex xs ->
       exists e,
         eIndex e = i /\
         In e xs) /\
    (forall e,
       In e xs ->
       lo < eIndex e).

Lemma findGtIndex_contiguous : forall entries x, sorted entries -> (forall i, 0 < i <= maxIndex entries -> (exists e, In e entries /\ eIndex e = i)) -> forall i, x < i <= maxIndex entries -> exists e, In e (findGtIndex entries x) /\ eIndex e = i.