Differences between revisions 5 and 6
 ⇤ ← Revision 5 as of 2019-11-22 20:01:09 → Size: 1888 Editor: XmlRpcBot Comment: ← Revision 6 as of 2019-11-22 22:30:43 → ⇥ Size: 1890 Editor: XmlRpcBot Comment: Deletions are marked like this. Additions are marked like this. Line 11: Line 11: [https://ai.dmi.unibas.ch/papers/helmert-et-al-icaps2007.pdf Flexible Abstraction Heuristics for Optimal Sequential Planning].<
> [[https://ai.dmi.unibas.ch/papers/helmert-et-al-icaps2007.pdf|Flexible Abstraction Heuristics for Optimal Sequential Planning]].<
>

This page describes the available merge trees that can be used to precompute a merge strategy, either for the entire task or a given subset of transition systems of a given factored transition system. Merge trees are typically used in the merge strategy of type 'precomputed', but they can also be used as fallback merge strategies in 'combined' merge strategies.

## Linear merge trees

These merge trees implement several linear merge orders, which are described in the paper:

`linear(random_seed=-1, update_option=use_random, variable_order=CG_GOAL_LEVEL)`
• random_seed (int [-1, infinity]): Set to -1 (default) to use the global random number generator. Set to any other value to use a local random number generator with the given seed.

• update_option ({use_first, use_second, use_random}): When the merge tree is used within another merge strategy, how should it be updated when a merge different to a merge from the tree is performed: choose among use_first, use_second, and use_random to choose which node of the tree should survive and represent the new merged index. Specify use_first (use_second) to let the node represententing the index that would have been merged earlier (later) survive. use_random chooses a random node.

• variable_order ({CG_GOAL_LEVEL, CG_GOAL_RANDOM, GOAL_CG_LEVEL, RANDOM, LEVEL, REVERSE_LEVEL}): the order in which atomic transition systems are merged

FastDownward: Doc/MergeTree (last edited 2021-08-06 16:41:03 by XmlRpcBot)