About this article
Published Online: Jun 18, 2022
Page range: 63 - 67
Received: Mar 31, 2022
Accepted: May 15, 2022
DOI: https://doi.org/10.2478/puma-2022-0010
Keywords
© 2022 Lapo Cioni, published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.
Following the footprints of what has been done with other sorting devices, we study a popqueue and define an optimal sorting algorithm, called Cons. Our results include a description of the set of all the preimages of a given permutation, an enumeration of the set of the preimages of permutations with some specific properties and, finally, the exact enumeration of permutations having 0, 1 and 2 preimages, respectively, with a characterization of permutations having 3 preimages.