5 research outputs found
The feasible region for consecutive patterns of permutations is a cycle polytope
We study proportions of consecutive occurrences of permutations of a given
size. Specifically, the feasible limits of such proportions on large
permutations form a region, called feasible region. We show that this feasible
region is a polytope, more precisely the cycle polytope of a specific graph
called overlap graph. This allows us to compute the dimension, vertices and
faces of the polytope.
Finally, we prove that the limits of classical occurrences and consecutive
occurrences are independent, in some sense made precise in the extended
abstract. As a consequence, the scaling limit of a sequence of permutations
induces no constraints on the local limit and vice versa.Comment: New version including referee's corrections. This is an extended
abstract of arXiv:1910.02233 for FPSAC 2020 (accepted for publication in a
proceedings volume of S\'eminaire Lotharingien Combinatoire
Densities in large permutations and parameter testing
A classical theorem of Erdős, Lovász and Spencer asserts that the densities of connected subgraphs in large graphs are independent. We prove an analogue of this theorem for permutations and we then apply the methods used in the proof to give an example of a finitely approximable permutation parameter that is not finitely forcible. The latter answers a question posed by two of the authors and Moreira and Sampaio