The author would like to correct some text in the article above:
Page 4, line 24:-
Assumption 1 (Downward trade-off). For any triple
$O_{i-1}$
,
$O_i$
,
$O_{i+1} \in {\bf O}$
and for any
$p \in (0, 1)$
, there is a
$q \in (0,1)$
such that:

Should read:-
Assumption 1 (Downward trade-off). For any triple
$O_{j-1}$
,
$O_j$
,
$O_i \in {\bf {\it O}}$
, where
$j < i$
, and for any
$p \in (0, 1)$
, there is a
$q \in (0, 1)$
such that:

Page 6, line 16:-
Assumption 2 (Upward trade-off). For any triple
$O_{j-1}$
,
$O_j$
,
$O_{j+1} \in {\bf {\it O}}$
and for any
$p \in (0, 1)$
, there is a
$q \in (0, 1)$
such that:

Should read:-
Assumption 2 (Upward trade-off). For any triple
$O_j$
,
$O_i$
,
$O_{i+1} \in {\bf {\it O}}$
, where
$j < i$
, and for any
$p \in (0, 1)$
, there is a
$q \in (0, 1)$
such that:

The author would like to apologize for this error.