Authors: Maurice Margenstern
Keywords: Hyperbolic tessellations, algorithmic approach.
Abstract
In this paper we revisit Poincare's theorem in the light of the splitting method which was introduced by the author in [3]. This led to the definition of combinatoric tilings.
We show that all tessellations which are constructed on a triangle with interior angles
and
with
are combinatoric, except when p=2 and q=3. At the price of a small extension of the definition of a combinatoric tiling, which we call quasi-combinatoric, we show that all tessellations with the above numbers p, q and r are quasi-combinatoric for all possible values of p, q and r, the case when p=2 and q=3 being included. As a consequence, see [3, 8], there is a bijection of the tiling being restricted to an angular sector S
0 and a tree which we call the spanning tree of the splitting. According , there is also a polynomial P
p,q,r which allows us to compute the number of triangles which are associated with the nodes of the n
th level in the tree: this will be examined in the second part of the paper. We also show that the tessellations which are constructed on an isosceles triangle with interior angles
, p odd, for the vertex angle and
for the basis angles with
are quasi-combinatoric and indeed combinatoric for p>=5. However, all the tessellations which are constructed on an equilateral triangle with interior angle
are combinatoric tilings.
LITA, EA 3097,
Universite de Metz,
Ile du Saulcy,
57045 Metz Cedex, France
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