Find the functional dependencies that hold in a relation There is a question in my book that asks the following:

Suppose we have relation R ( A ,B ,C ,D ,E ) , with some set of FD’s, and we wish to project those FD’s onto relation S(A, B, C). Give the
    FD’s that hold in S if the FD’s for R are:  

A-&gt;D
BD-&gt;E
AC-&gt;E
DE-&gt;B


In each case, it is sufficient to give a minimal basis for the full set of FD’s of S.

So I attempted to compute the closure of attributes for all of the subsets of (A,B,C).  I could not find any minimal basis of FD's for S.  I computer the closure of A, B, C, and AC, but I could not get all of the attributes.  A only implies AD, B only implies B, C only implies C and AC only implies ACE.  I could not find a functional dependency where there is a attribute on the left hand side that implies all of the attributes on the right hand side.
For convenience, define the (implied) numbering of your question:


A->D
BD->E
AC->E
DE->B


Then substituting 1 and 3 into 4 gives
(A)(AC) -> B
which reduces to just
 5. AC -> B.