# Haruspicy 3: The anisotropic generating function of directed bond-animals is not D-finite

• Published in 2006
In the collections
While directed site-animals have been solved on several lattices, directed bond-animals remain unsolved on any nontrivial lattice. In this paper we demonstrate that the anisotropic generating function of directed bond-animals on the square lattice is fundamentally different from that of directed site-animals in that it is not differentiably finite. We also extend this result to directed bond-animals on hypercubic lattices. This indicates that directed bond-animals are unlikely to be solved by similar methods to those used in the solution of directed site-animals. It also implies that a solution cannot be conjectured using computer packages such as Gfun [A Maple package developed by B. Salvy, P. Zimmermann, E. Murray at INRIA, France, available from http://algo.inria.fr/libraries/ at time of submission; B. Salvy, P. Zimmermann, Gfun: A Maple package for the manipulation of generating and holonomic functions in one variable, ACM Trans. Math. Software 20 (2) (1994) 163–177] or differential approximants [A.J. Guttmann, Asymptotic analysis of coefficients, in: C. Domb, J. Lebowitz (Eds.), Phase Transit. Crit. Phenom., vol. 13, Academic Press, London, 1989, pp. 1–234, programs available from http://www.ms.unimelb.edu.au/~tonyg].

## Other information

issn
00973165
journal
Journal of Combinatorial Theory, Series A
keywords
Bond animals,Differentiably finite power series,Enumeration,Solvability
number
6
pages
1031--1049
volume
113

### BibTeX entry

@article{Rechnitzer2006,
title = {Haruspicy 3: The anisotropic generating function of directed bond-animals is not D-finite},
author = {Rechnitzer, Andrew},
url = {http://www.sciencedirect.com/science/article/pii/S0097316505001883},
urldate = {2015-11-08},
abstract = {While directed site-animals have been solved on several lattices, directed bond-animals remain unsolved on any nontrivial lattice. In this paper we demonstrate that the anisotropic generating function of directed bond-animals on the square lattice is fundamentally different from that of directed site-animals in that it is not differentiably finite. We also extend this result to directed bond-animals on hypercubic lattices. This indicates that directed bond-animals are unlikely to be solved by similar methods to those used in the solution of directed site-animals. It also implies that a solution cannot be conjectured using computer packages such as Gfun [A Maple package developed by B. Salvy, P. Zimmermann, E. Murray at INRIA, France, available from http://algo.inria.fr/libraries/ at time of submission; B. Salvy, P. Zimmermann, Gfun: A Maple package for the manipulation of generating and holonomic functions in one variable, ACM Trans. Math. Software 20 (2) (1994) 163–177] or differential approximants [A.J. Guttmann, Asymptotic analysis of coefficients, in: C. Domb, J. Lebowitz (Eds.), Phase Transit. Crit. Phenom., vol. 13, Academic Press, London, 1989, pp. 1–234, programs available from http://www.ms.unimelb.edu.au/{\~{}}tonyg].},
comment = {},
issn = 00973165,
journal = {Journal of Combinatorial Theory, Series A},
keywords = {Bond animals,Differentiably finite power series,Enumeration,Solvability},
month = {aug},
number = 6,
pages = {1031--1049},
volume = 113,
year = 2006,
collections = {Animals,Attention-grabbing titles}
}