Transitive Amstrong Rules
From the definition of transitive dependency -

A functional dependency is said to be transitive if it is indirectly formed by two functional dependencies. For e.g.

X -> Z is a transitive dependency if the following three functional dependencies hold true:

X-&gt;Y
Y does not -&gt;X
Y-&gt;Z


Given, ABCD->E and AC->ABCD, or simply AC->BD

So, ABCD -> E can be written as AC -> E, as AC->BD.

So, the transitive rule is not required to prove AC -> E

Also, if we take X= AC, Y=ABCD, then X->Y (given) but X is subset of Y

So, Y->X (failing the second rule for transitivity)