Answered! Consider the set of rights(read,write,execute ,append,list,modify,own)….

(a)

The command delete_all_rights (p,q,s) that causes p to delete all rights the subject q has over object s.

command delete_all_rights(p, q, s)

delete read from a[q, s];

delete write from a[q, s];

delete execute from a[q, s];

delete append from a[q, s];

delete list from a[q, s];

delete modify from a[q, s];

delete own from a[q, s];

end

(b)

The modified command that causes the deletion only if p has modify rights over s:

command delete_all_rights(p,q,s)

if modify in a[p,s] then

delete read in a[q,s]

delete write in a[q,s]

delete execute in a[q,s]

delete append in a[q,s]

delete list in a[q,s]

delete modify in a[q,s]

delete own in a[q,s]

end