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%
%  This file is part of Logtalk <https://logtalk.org/>
%  Copyright 1998-2021 Paulo Moura <pmoura@logtalk.org>
%  SPDX-License-Identifier: Apache-2.0
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%  you may not use this file except in compliance with the License.
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%      http://www.apache.org/licenses/LICENSE-2.0
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% reversing a list twice must give the original list
reverse_2_twice_prop(List) :-
	list::reverse(List, Reverse),
	list::reverse(Reverse, ReverseReverse),
	List == ReverseReverse.

% same_length/2 must be true when using the same list for both arguments
same_length_2_prop(List) :-
	list::same_length(List, List).

% the length of two lists of the same length must be an non-negative integer
same_length_3_prop(List) :-
	list::same_length(List, _, Length),
	Length >= 0.

% a broken property just to check the return of a counter-example that falsifies it
broken_nth1_3_prop(List) :-
	list::nth1(Position, List, _),
	list::length(List, Length),
	Position > Length.
