It is known that, through hodograph (reciprocal) transformation, Degasperis-Procesi
(DP) equations is linked to the negative flow of the Kaup-Kuperschmidt (KK) hierarchy
while the Novikov equation is connected to the negative flow of the Sawada-Kotera (SK) hierarchy.
Both the solutions of the KK and SK equations are linked to the solution of
the modified KK equation. In this talk, we will show how to derive the DP equation and
Novikov equation from the pseudo-3 reductions of the CKP and BKP hierarchies, respectively
and reveal an unified tau-function structure behind the DP and Novikov equations with a
standard pfaffian lattice as the building blocks.