Gao's dyadic density-one coalescence conjecture
Abstract
We give a short proof of the density-one assertion posed by Gao for consecutive Collatz starts, independent of the first public proof, due to Said Duran (September 2026). Let C be the ordinary map and let H(n, m) count halving branches among the first m ordinary steps. Write Gk(n) when n and n+1 have, by time k, a common endpoint, equal halving counts, and have stayed above one up to that endpoint. If d̄k = 2−k·#{1 ≤ n < 2k − 1 : Gk(n)}, then d̄k → 1. A uniform absorption estimate for the 2-adic pair process gives the quantitative estimate 1 − d̄k = O(k−1/2), and the exact leading constant is determined in a companion paper. The argument concerns synchronization of two paths; it proves neither termination of every path nor the Collatz conjecture. Companion papers: Exact rates in Collatz synchronization; Quantitative synchronization of Collatz trajectories; The stochastic 3x+1 model is a theorem: Brownian structure of Collatz orbits.
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BibTeX
@misc{leen2026gaos,
title = {{Gao's dyadic density-one coalescence conjecture}},
author = {David Leen},
howpublished = {Zenodo (CERN European Organization for Nuclear Research)},
year = {2026},
month = oct,
doi = {10.5281/zenodo.23268761},
url = {https://doi.org/10.5281/zenodo.23268761},
note = {CC BY},
}
RIS
TY - UNPB
TI - Gao's dyadic density-one coalescence conjecture
AU - David Leen
PY - 2026
DA - 2026/10/09
PB - Zenodo (CERN European Organization for Nuclear Research)
DO - 10.5281/zenodo.23268761
UR - https://doi.org/10.5281/zenodo.23268761
AB - We give a short proof of the density-one assertion posed by Gao for consecutive Collatz starts, independent of the first public proof, due to Said Duran (September 2026). Let C be the ordinary map and let H(n, m) count halving branches among the first m ordinary steps. Write Gk(n) when n and n+1 have, by time k, a common endpoint, equal halving counts, and have stayed above one up to that endpoint. If d̄k = 2−k·#{1 ≤ n < 2k − 1 : Gk(n)}, then d̄k → 1. A uniform absorption estimate for the 2-adic pair process gives the quantitative estimate 1 − d̄k = O(k−1/2), and the exact leading constant is determined in a companion paper. The argument concerns synchronization of two paths; it proves neither termination of every path nor the Collatz conjecture. Companion papers: Exact rates in Collatz synchronization; Quantitative synchronization of Collatz trajectories; The stochastic 3x+1 model is a theorem: Brownian structure of Collatz orbits.
ER -