Translate the propositions of the following sorites into standard form, and test the validity of each sorites.

(1) The only books in this library that I do not recommend for reading are unhealthy in tone.
(2) The bound books are all well written.
(3) All the romances are healthy in tone.
(4) I do not recommend that you read any of the unbound books.
Therefore all the romances in this library are well written.