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`prefix_span_pattern_miner`
=============

PrefixSpan sequential pattern miner for sequence datasets. The library
depends on the `sequential_pattern_mining_protocols` support library,
implements the generic `pattern_miner_protocol` defined in the
`pattern_mining_protocols` core library, and mines frequent sequential
patterns using recursive projected databases with both same-event and
next-event extensions.

Requires a dataset implementing `sequence_dataset_protocol` with
sequences represented as ordered lists of canonical sorted itemsets
over a declared item domain.


API documentation
-----------------

Open the [../../apis/library_index.html#prefix_span_pattern_miner](../../apis/library_index.html#prefix_span_pattern_miner)
link in a web browser.


Loading
-------

To load this library, load the `loader.lgt` file:

	| ?- logtalk_load(prefix_span_pattern_miner(loader)).


Testing
-------

To test this library predicates, load the `tester.lgt` file:

	| ?- logtalk_load(prefix_span_pattern_miner(tester)).


Features
--------

- **Projected Database Mining**: Mines sequential patterns by recursively projecting suffix databases.
- **Itemset and Sequence Extensions**: Supports both extending the last itemset and appending a new singleton itemset.
- **Canonical Sequences**: Validates that itemsets are sorted, duplicate-free, non-empty, and restricted to declared items.
- **Flexible Support Thresholds**: Supports minimum support specified either as a relative proportion or as an absolute count.
- **Model Export**: Mined pattern collections can be exported as predicate clauses or written to a file.


Options
-------

The `mine/3` predicate accepts the following options:

- `minimum_support/1`: Relative minimum support threshold in the interval `]0.0, 1.0]`. The default is `0.5`.
- `minimum_support_count/1`: Absolute minimum support count. When both support options are provided, this option takes precedence.
- `maximum_pattern_length/1`: Maximum total number of items in a mined sequential pattern. The default is `1000`, effectively capped by the longest sequence in the dataset.
- `minimum_pattern_length/1`: Minimum total number of items retained in the mined result. The default is `1`.


Pattern miner representation
----------------------------

The mined pattern miner result is represented by a compound term with
the functor chosen by the implementation and arity 3. For example:

	prefix_span_pattern_miner(ItemDomain, Patterns, Options)

Where:

- `ItemDomain`: Canonical sorted list of declared dataset items.
- `Patterns`: List of `sequence_pattern(Pattern, SupportCount)` terms ordered first by total item count and then lexicographically.
- `Options`: Effective mining options used to mine the frequent sequential patterns.


References
----------

1. Pei, J., Han, J., Mortazavi-Asl, B., et al. (2001) - "PrefixSpan: Mining sequential patterns efficiently by prefix-projected pattern growth".
