Conclusion: Heuristic functions that produce negative values are not inadmissible, per se, but have the potential to break the guarantees of A*. Interesting question. Fundamentally, the only requirement for admissibility is that a heuristic never over-estimates the distance to the goal. This is important, because an overestimate in the wrong...

time-series,forecasting,state-space

The state vector is exactly the same in the multiplicative case as in the additive case. All the equations are given here: https://www.otexts.org/fpp/7/7 For the ETS(M,Md,N) model, ...