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Pack logtalk -- logtalk-3.101.0/library/derangements/NOTES.md

This file is part of Logtalk https://logtalk.org/ SPDX-FileCopyrightText: 1998-2026 Paulo Moura <pmoura@logtalk.org> SPDX-License-Identifier: Apache-2.0

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

derangements

This library provides predicates for generating and querying derangements over lists. Derangements are full-length permutations where no result element is identical to the input element at the same position. The following categories of predicates are provided:

  • Generation operations - Predicates for generating derangements.
  • Ordering variants - Predicates that support an additional order argument (default, lexicographic, or shortlex) for controlling output order.
  • Distinct-value generation - Predicates for generating derangements while deduplicating equal-valued results.
  • Indexed access - Predicates for direct access to derangements at specific positions, including distinct derangements.
  • Lexicographic stepping - Predicates for navigating derangements in lexicographic order.
  • Counting operations - Predicates for counting derangements and distinct derangements.
  • Random selection - Predicates for randomly selecting and sampling derangements and distinct derangements. Dedicated permutations, arrangements, cartesian_products, combinations, multisets, partitions, and subsequences libraries are also available for focused APIs on related operations.

API documentation

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

Loading

To load all entities in this library, load the loader.lgt file:

| ?- logtalk_load(derangements(loader)).

Testing

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

| ?- logtalk_load(derangements(tester)).