How can we prove $\bigtriangledown = \bigtriangleup E^{-1}$?
where,$\bigtriangleup \rightarrow \text{ Forward difference operator }$ $\bigtriangledown \rightarrow \text{ Backward difference operator }$ $E \rightarrow \text{ Shift operator }$ I tried to utilize the method of seperation of symbol but not quite there...
Give some hints for this proof.