Link to this article: http://journals.cambridge.org/abstract_S0143385710000404How to cite this article: YUKI YAYAMA (2011). Existence of a measurable saturated compensation function between subshifts and its applications.Abstract. We show the existence of a bounded Borel measurable saturated compensation function for any factor map between subshifts. As an application, we find the Hausdorff dimension and measures of full Hausdorff dimension for a compact invariant set of an expanding non-conformal map on the torus given by an integer-valued diagonal matrix. These problems were studied in [23] for a compact invariant set whose symbolic representation is a shift of finite type under the condition of the existence of a saturated compensation function. By using the ergodic equilibrium states of a constant multiple of a Borel measurable compensation function, we extend the results to the general case where this condition might not hold, presenting a formula for the Hausdorff dimension for a compact invariant set whose symbolic representation is a subshift and studying invariant ergodic measures of full dimension. We study uniqueness and properties of such measures for a compact invariant set whose symbolic representation is a topologically mixing shift of finite type. Downloaded: 16 Mar 2015 IP address: 132.174.255.116 1564 Y. Yayama given by Shin [19] and necessary and sufficient conditions for the existence of a saturated compensation function were also studied by Shin [18]. In this paper, we first consider a Borel measurable function F : X → R that satisfies equation (1.1). If there is such an F, we say that F is a Borel measurable compensation function. F is a Borel measurable saturated compensation functionsubshifts there always exists a bounded Borel measurable saturated compensation function and characterize the equilibrium states. Replacing F in equation (1.1) by this Borel measurable compensation function, in Theorem 3.9 we also show that equation (1.1) holds for a larger class of potentials on Y called subadditive potentials (see §1 for the definition of subadditive potentials). Using Borel measurable saturated compensation functions, we then study for a fixed α > 0 the measures that maximize the weighted entropy functional φ αFinding such measures is useful in problems on Hausdorff dimension (see [8]). When there is a saturated compensation function between subshifts, the measures that maximize φ α are, according to Shin [20], the equilibrium states of a constant multiple of a saturated compensation function. We extend the results for any subshifts without assuming the existence of a saturated compensation function (Proposition 3.14 and Theorem 3.15).As an application, we study the problem on dimensions of compact invariant sets of non-conformal expanding maps; in particular, we consider the endomorphism of the torus given by T (x, y) = (lx mod 1, my mod 1), l > m ≥ 2, l, m ∈ N. Throughout this paper, by a measure µ of full dimension for a compact T -invariant set K , we mean that µ is a Borel probability m...