Differences between revisions 13 and 14
 ⇤ ← Revision 13 as of 2017-04-25 15:20:24 → Size: 3896 Editor: XmlRpcBot Comment: ← Revision 14 as of 2019-03-02 21:34:34 → ⇥ Size: 4270 Editor: XmlRpcBot Comment: Deletions are marked like this. Additions are marked like this. Line 39: Line 39: == Standard open list ==Standard open list that uses a single evaluator == Best-first open list ==Open list that uses a single evaluator and FIFO tiebreaking. Line 48: Line 48: '''Implementation Notes:''' Elements with the same evaluator value are stored in double-ended queues, called "buckets". The open list stores a map from evaluator values to buckets. Pushing and popping from a bucket runs in constant time. Therefore, inserting and removing an entry from the open list takes time O(log(n)), where n is the number of buckets.

## Alternation open list

alternates between several open lists.

`alt(sublists, boost=0)`
• sublists (list of OpenList): open lists between which this one alternates

• boost (int): boost value for contained open lists that are restricted to preferred successors

## Epsilon-greedy open list

Chooses an entry uniformly randomly with probability 'epsilon', otherwise it returns the minimum entry. The algorithm is based on

`epsilon_greedy(eval, pref_only=false, epsilon=0.2, random_seed=-1)`
• eval (Evaluator): evaluator

• pref_only (bool): insert only nodes generated by preferred operators

• epsilon (double [0.0, 1.0]): probability for choosing the next entry randomly

• 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.

## Pareto open list

Selects one of the Pareto-optimal (regarding the sub-evaluators) entries for removal.

`pareto(evals, pref_only=false, state_uniform_selection=false, random_seed=-1)`
• evals (list of Evaluator): evaluators

• pref_only (bool): insert only nodes generated by preferred operators

• state_uniform_selection (bool): When removing an entry, we select a non-dominated bucket and return its oldest entry. If this option is false, we select uniformly from the non-dominated buckets; if the option is true, we weight the buckets with the number of entries.

• 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.

## Best-first open list

Open list that uses a single evaluator and FIFO tiebreaking.

`single(eval, pref_only=false)`
• eval (Evaluator): evaluator

• pref_only (bool): insert only nodes generated by preferred operators

Implementation Notes: Elements with the same evaluator value are stored in double-ended queues, called "buckets". The open list stores a map from evaluator values to buckets. Pushing and popping from a bucket runs in constant time. Therefore, inserting and removing an entry from the open list takes time O(log(n)), where n is the number of buckets.

## Tie-breaking open list

`tiebreaking(evals, pref_only=false, unsafe_pruning=true)`
• evals (list of Evaluator): evaluators

• pref_only (bool): insert only nodes generated by preferred operators

• unsafe_pruning (bool): allow unsafe pruning when the main evaluator regards a state a dead end

## Type-based open list

Uses multiple evaluators to assign entries to buckets. All entries in a bucket have the same evaluator values. When retrieving an entry, a bucket is chosen uniformly at random and one of the contained entries is selected uniformly randomly. The algorithm is based on

`type_based(evaluators, random_seed=-1)`
• evaluators (list of Evaluator): Evaluators used to determine the bucket for each entry.

• 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.

FastDownward: Doc/OpenList (last edited 2019-03-08 12:08:33 by XmlRpcBot)