A growth model based on the arithmetic $Z$-game

Abstract

We present an evolutionary self-governing model based on the numerical atomic rule $Z(a,b)=ab/\gcd (a,b{)}^2$, for $a,b$ positive integers. Starting with a sequence of numbers, the initial generation $Gin$, a new sequence is obtained by applying the $Z$-rule to any neighbor terms. Likewise, applying repeatedly the same procedure to the newest generation, an entire matrix $T_{Gin}$ is generated. Most often, this matrix, which is the recorder of the whole process, shows a fractal aspect and has intriguing properties. If $Gin$ is the sequence of positive integers, in the associated matrix remarkable are the distinguished geometrical figures called the $Z$-solitons and the sinuous evolution of the size of numbers on the western edge. We observe that $T_{{\mathbb{N}}^{\ast }}$ is close to the analogue free of solitons matrix generated from an initial generation in which each natural number is replaced by its largest divisor that is a product of distinct primes. We describe the shape and the properties of this new matrix. N. J. A. Sloane raised a few interesting problems regarding the western edge of the matrix $T_{{\mathbb{N}}^{\ast }}$. We solve one of them and present arguments for a precise conjecture on another.

20 pages, 9 figures

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