Solving the $106$ years old $3^k$ points problem with the clockwise-algorithm

Fuente: arXiv
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Autor principal: Ripà, Marco
Formato: Preprint
Publicado: 2024
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author Ripà, Marco
author_facet Ripà, Marco
contents In this paper, we present the clockwise-algorithm that solves the extension in $k$-dimensions of the infamous nine-dot problem, the well-known two-dimensional thinking outside the box puzzle. We describe a general strategy that constructively produces minimum length covering trails, for any $k \in \mathbb{N}-\{0\}$, solving the NP-complete $(3 \times 3 \times \cdots \times 3)$-point problem inside $3 \times 3 \times \cdots \times 3$ hypercubes. In particular, using our algorithm, we explicitly draw different covering trails of minimal length $h(k)=\frac{3^k-1}{2}$, for $k=3, 4, 5$. Furthermore, we conjecture that, for every $k \geq 1$, it is possible to solve the $3^k$-point problem with $h(k)$ lines starting from any of the $3^k$ nodes, except from the central one. Finally, we cover a $3 \times 3 \times 3$ grid with a tree of size $12$.
format Preprint
id arxiv_https___arxiv_org_abs_2401_10163
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Solving the $106$ years old $3^k$ points problem with the clockwise-algorithm
Ripà, Marco
General Mathematics
05C85 (Primary) 05C57, 68R10 (Secondary)
In this paper, we present the clockwise-algorithm that solves the extension in $k$-dimensions of the infamous nine-dot problem, the well-known two-dimensional thinking outside the box puzzle. We describe a general strategy that constructively produces minimum length covering trails, for any $k \in \mathbb{N}-\{0\}$, solving the NP-complete $(3 \times 3 \times \cdots \times 3)$-point problem inside $3 \times 3 \times \cdots \times 3$ hypercubes. In particular, using our algorithm, we explicitly draw different covering trails of minimal length $h(k)=\frac{3^k-1}{2}$, for $k=3, 4, 5$. Furthermore, we conjecture that, for every $k \geq 1$, it is possible to solve the $3^k$-point problem with $h(k)$ lines starting from any of the $3^k$ nodes, except from the central one. Finally, we cover a $3 \times 3 \times 3$ grid with a tree of size $12$.
title Solving the $106$ years old $3^k$ points problem with the clockwise-algorithm
topic General Mathematics
05C85 (Primary) 05C57, 68R10 (Secondary)
url https://arxiv.org/abs/2401.10163