In this paper, we look at how to count the number of elements of a set within
the frame of Sergeyev's numeral system. We also look at the connection between
the number of elements of a set and the notion of bijection in this new
setting. We also show the difference between this new numeral system and the
results of the traditional naive set theory.
In this paper, we look at the improvement of our knowledge on a family of
tilings of the hyperbolic plane which is brought in by the use of Sergeyev's
numeral system based on grossone. It appears that the information we can get by
using this new numeral system depends on the way we look at the tilings. The
ways are significantly different but they confirm some results which were
obtained in the traditional but constructive frame and allow us to obtain an
additional precision with respect to this information.
In this paper, following the way opened by a previous paper deposited on
arXiv, we give an upper bound to the number of states for a hyperbolic cellular
automaton in the pentagrid. Indeed, we prove that there is a hyperbolic
cellular automaton which is rotation invariant and whose halting problem is
undecidable and which has 9~states.
In this paper, we show a construction of a weakly universal cellular
automaton in the 3D hyperbolic space with two states. The cellular automaton is
rotation invariant and, moreover, based on a new implementation of a railway
circuit in the dodecagrid,the construction is a truly 3D-one.
In this paper, we look at two ways to implement determinisitic one
dimensional cellular automata into hyperbolic cellular automata in three
contexts: the pentagrid, the heptagrid and the dodecagrid, these tilings being
classically denoted by $\{5,4\}$, $\{7,3\}$ and $\{5,3,4\}$ respectively.
This paper introduces a method of navigation in a large family of tilings of
the hyperbolic plane and looks at the question of possible applications in the
light of the few ones which were already obtained.