Multifractal analysis of Lyapunov exponent for the backward continued fraction map

In this note we study the multifractal spectrum of Lyapunov exponents for interval maps with infinitely many branches and a parabolic fixed point. It turns out that, in strong contrast with the hyperbolic case, the domain of the spectrum is unbounded and points of non-differentiability might exist. Moreover, the spectrum is not concave. We establish conditions that ensure the existence of inflection points. We also study the thermodynamic formalism for such maps. We prove that the pressure function is real analytic in a certain interval and then it becomes equal to zero

Thermodynamic formalism for the positive geodesic flow on the modular surface

In this note we study the thermodynamic formalism for the positive geodesic flow on the modular surface. We define the pressure and prove the variational principle. We also establish conditions for the the pressure to be real analytic and for the potentials to have unique equilibrium states. The results in this paper were largely superceded by "Phase transitions for suspension flows" by Iommi and Jordan arXiv:1202.0849Comment: This note is not intended for publication. It was largely superceded by the paper "Phase transitions for suspension flows" by Iommi and Jordan, arXiv:1202.084

An elementary non-recursive expression for the partition function P(n)

Consideration of a classification of the number of partitions of a natural number according to the members of sub-partitions differing from unity leads to a non-recursive formula for the number of irreducible representations of the symmetric group Sn. This article was published, long ago, under the title A non-recursive expression for the number of irreducible representations of the Symmetric Group Sn, Physica 114A, 1982, 361-364, North-Holland Publishing Co. The Introduction has been, somewhat, improved, however, the handmade result remains unproved.Comment: 5 pages, 2 figure

Branching rules for the Weyl Groups of the Unitary and Orthogonal Lie Groups

This note presents a procedure to determine the reduction of the irreducible and the induced characters of the symmetric group in terms of the irreducible and induced characters of the hyperoctahedral group Key Words: Symmetric Group, Hyperoctahedral group, Representations, Characters, Re- duction.Comment: 14 page

Symbolic Languages and Ars Combinatoria

This article analyses some paragraphs of the Dissertatio de Arte Combinatoria (1666) where G.W. Leibniz considers the syntax of a language with a given number of primitive terms. We propose a new formulation which generalizes the philosopher conception of such a formal system.Comment: 10 pages, 2 figure

Thermodynamic formalism for interval maps: inducing schemes

This survey article concerns inducing schemes in the context of interval maps. We explain how the study of these induced systems allows for the fine description of, not only, the thermodynamic formalism for certain multimodal maps, but also of its multifractal structure.Comment: Surve

Zero temperature limits of Gibbs states for almost-additive potentials

This paper is devoted to study ergodic optimisation problems for almost-additive sequences of functions (rather than a fixed potential) defined over countable Markov shifts (that is a non-compact space). Under certain assumptions we prove that any accumulation point of a family of Gibbs equilibrium measures is a maximising measure. Applications are given in the study of the joint spectral radius and to multifractal analysis of Lyapunov exponent of non-conformal maps.Comment: Changes in Sections 4 and 5 are included in this versio

Transience in Dynamical Systems

We extend the theory of transience to general dynamical systems with no Markov structure assumed. This is linked to the theory of phase transitions. We also provide examples of new kinds of transient behaviour.Comment: Changes have been made mostly in Sections 1 and

Time change for flows and thermodynamic formalism

This paper is devoted to study how do thermodynamic formalism quantities varies for time changes of suspension flows defined over countable Markov shifts. We prove that in general no quantity is preserved. We also make a topological description of the space of suspension flows according to certain thermodynamic quantities. For example, we show that the set of suspension flows defined over the full shift on a countable alphabet having finite entropy is open. Of independent interest might be a set of analytic tools we use to construct examples with prescribed thermodynamic behaviour

Pressure, Poincar\'e series and box dimension of the boundary

In this note we prove two related results. First, we show that for certain Markov interval maps with infinitely many branches the upper box dimension of the boundary can be read from the pressure of the geometric potential. Secondly, we prove that the box dimension of the set of iterates of a point in H^n with respect to a parabolic subgroup of isometries equals the critical exponent of the Poincare series of the associated group. This establishes a relationship between the entropy at infinity and dimension theory.Comment: Introduction has been rewritten. Comments welcom