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Résumé
We here elaborate on a quantitative argument to support the validity of the Collatz conjecture, also known as the (3x+1)
or Syracuse conjecture. The analysis is structured as follows. First, three distinct fixed points are found for the third iterate of the Collatz map, which hence organise in a period 3 orbit of the original map. These are 1, 2 and 4, the elements which define the unique attracting cycle, as hypothesised by Collatz. To carry out the calculation we write the positive integers in modulo 8 (mod8), obtain a closed analytical form for the associated map and determine the transitions that yield contracting or expanding iterates in the original, infinitedimensional, space of positive integers. Then, we consider a Markov chain which runs on the reduced space of mod8 congruence classes of integers. The transition probabilities of the Markov chain are computed from the deterministic map, by employing a measure that is invariant for the map itself. Working in this setting, we demonstrate that the stationary distribution sampled by the stochastic system induces a contracting behaviour for the orbits of the deterministic map on the original space of the positive integers. Sampling the equilibrium distribution on the congruence classes mod 8^m
for any m, which amounts to arbitrarily reducing the degree of imposed coarse graining, returns an identical conclusion.
or Syracuse conjecture. The analysis is structured as follows. First, three distinct fixed points are found for the third iterate of the Collatz map, which hence organise in a period 3 orbit of the original map. These are 1, 2 and 4, the elements which define the unique attracting cycle, as hypothesised by Collatz. To carry out the calculation we write the positive integers in modulo 8 (mod8), obtain a closed analytical form for the associated map and determine the transitions that yield contracting or expanding iterates in the original, infinitedimensional, space of positive integers. Then, we consider a Markov chain which runs on the reduced space of mod8 congruence classes of integers. The transition probabilities of the Markov chain are computed from the deterministic map, by employing a measure that is invariant for the map itself. Working in this setting, we demonstrate that the stationary distribution sampled by the stochastic system induces a contracting behaviour for the orbits of the deterministic map on the original space of the positive integers. Sampling the equilibrium distribution on the congruence classes mod 8^m
for any m, which amounts to arbitrarily reducing the degree of imposed coarse graining, returns an identical conclusion.
langue originale  Anglais 

Pages (de  à)  445468 
Nombre de pages  24 
journal  Bollettino dell'Unione Matematica Italiana 
Volume  11 
Numéro de publication  4 
Les DOIs  
Etat de la publication  Publié  3 oct. 2017 
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Projets
 1 Terminé

PAI n°P7/19  DYSCO: Dynamical systems, control and optimization (DYSCO)
WINKIN, J., Blondel, V., Vandewalle, J., Pintelon, R., Sepulchre, R., Vande Wouwer, A. & SARTENAER, A.
1/04/12 → 30/09/17
Projet: Recherche
Activités
 1 Participation à une conférence, un congrès

CCS 2016
Timoteo Carletti (Conférencier)
22 sept. 2016Activité: Types de Participation ou d'organisation d'un événement › Participation à une conférence, un congrès