h(P ) = h1(Pm): Alternative Characterisations of the Generalisation From hmax To h

The h (m = 1, . . .) family of admissible heuristics for STRIPS planning with additive costs generalise the h heuristic, which results when m = 1. We show that the step from h to h can be made by changing the planning problem instead of the heuristic function. This furthers our understanding of the h heuristic, and may inspire application of the same generalisation to admissible heuristics stronger than h. As an example, we show how it applies to the additive variant of h obtained via cost splitting.