How are layers counted?
How to count layers is a matter of considerable dispute. • Some people count layers of units. But of these people, some count the input layer and some don’t. • Some people count layers of weights. But I have no idea how they count skip-layer connections. To avoid ambiguity, you should speak of a 2-hidden-layer network, not a 4-layer network (as some would call it) or 3-layer network (as others would call it). And if the connections follow any pattern other than fully connecting each layer to the next and to no others, you should carefully specify the connections.
