Div(Y(1),...,Y(t),Ytarget(1),...,Ytarget(t)) ≠ ∑Div(Y(i),Ytarget(i))
Recurrence is not necessary.
http://www.hexahedria.com/2015/08/03/composing-music-with-recurrent-neural-networks/
P means Period(Section), I think.