Abstract Title: * Titius-Bode relations in the exoplanet systems Authors: * Ts. B. Georgiev Institution: * Institut of Astronomy and NAO Preferred format: * Oral Abstract Text: * The Titius-Bode law (TBL) establishes the regularity (near-commensurability) of orbital sizes or periods in the orbital systems. TBL has not been explained convincingly yet, but the correlations between the parameters of TBL and the parameters of the orbital system revealed in this paper may be useful. We created a computer method for objective numbering of the orbits and building of an optimal TBL model. The method is applied to 30 orbital systems, including 17 exoplanet systems We compare two geometric parameters of the TBL model, gradient and separability, with three physical parameters of the orbital system - mass of the central body, total mass of the orbiting bodies and (for planetary systems only) metallicity of the star. The gradient and the separability of the TBL model for exoplanet systems depend mainly on the total mass of the orbiting bodies, but this mass in the exoplanet systems correlates well with the metallicity of the star.The most remarkable are the the dependences of the TBL gradient on the mass of the central body and on the total mass of the orbiting bodies when the s\Solar Systems bodies are included. The first of them seems to be linear over 8 magnitudes of the masses of the central body. The second of them is fitted by 3-rd order polynomial over 10 magnitudes of the masses of the orbiting bodies.