Prove that the rule $$I would be unsound were it not for the

restriction that the rejected sentence s appear as an assumption. To prove

this, consider the modified rule:

$*$I

Input: s$,$ t$,$t

Output: $$s

Dependencies: combined dependencies of t and $$t$,$ minus dependencies of s

Show that using this rule one can prove some claim of the form s $|-$NK t

such that it is not true that s $|=$ t$.$