Is this partial dependency? I have this relation:

R = ABCDE
F: AB-&gt;DE, AC-&gt;B, DE-&gt;C, AE-&gt;C, C-&gt;AB.


Is AC->B a partial dependency in F?

I'm guessing it is, because 

C->AB can be decomposed to

C-&gt;A
C-&gt;B


from where we can conclude that there exists a subset of AC (C in our case) which goes into B, that is 

C->B.

I couldn't find a formal definition on the internet, so I would like it if someone could confirm my assumption.
In order for AC->B to be a partial key dependency, it has to satisfy these conditions.


AC must be a candidate key. (Not necessarily the primary key.)
One of these functional dependencies must hold.


A->B, or
C->B



So the first question I'd ask myself is, "Is AC a candidate key of F?"