Strategické chování při vstupu na trh

Bakalářská práce se zabývá chováním firem při možnosti vstupu na více trhů. Tato situace nastává často při expanzi firem nebo při zavedení nového výrobku. Použitý model je podobný modelu Bresnahana a Reisse (1990), který byl použit pro modelování vstupu na jeden trh za různých okolností. V této práci formulujeme podobný diskrétní model pro více trhů, abychom zjistili trh a množství výstupu, které si firma vybere. Model vstupu na trh s heterogenním produktem, dvěma firmami a N trhy je studován a porovnán se závěry pro jeden trh. Pro testování vstupu na více trhů je použit jednoduchý program na simulování různých struktur trhů.This thesis focuses on the behaviour of firms when choosing among multiple markets one to enter. This situation occurs frequently during expansions of firms or introduction of new products. The model used is similar to the model of a static entry game by Bresnahan and Reiss (1990), which was applied on single markets under various assumption to model the impact of market structure. In the thesis a similar discrete-choice model is formulated and studied under multiple markets, to determine the market and output a firm chooses. An entry model with heterogeneous products, 2 firms and N markets is studied and compared to findings about single market entry. To test various characteristics of the structure of markets a simple computer program is used to simulate market entry.Institute of Economic StudiesInstitut ekonomických studiíFaculty of Social SciencesFakulta sociálních vě

Cylindrically and toroidally symmetric solutions with a cosmological constant

Cylindrical-like coordinates for constant-curvature 3-spaces are introduced and discussed. This helps to clarify the geometrical properties, the coordinate ranges and the meaning of free parameters in the static vacuum solution of Linet and Tian. In particular, when the cosmological constant is positive, the spacetimes have toroidal symmetry. One of the two curvature singularities can be removed by matching the Linet-Tian vacuum solution across a toroidal surface to a corresponding region of the dust-filled Einstein static universe. Some other properties and limiting cases of these space-times are also described, together with their generalisation to higher dimensions.Comment: 4 pages, 2 figures. To appear in the Proceedings of The Spanish Relativity Meeting (ERE2010), Journal of Physics: Conference Serie

Relativistic Solenoids

We construct a general relativistic analogy of an infinite solenoid, i.e., of an infinite cylinder with zero electric charge and non-zero electric current in the direction tangential to the cylinder and perpendicular to its axis. We further show that the solution has a good weak-field limit.Comment: 9 pages, 2 figure

General Kundt spacetimes in higher dimensions

We investigate a general metric of the Kundt class of spacetimes in higher dimensions. Geometrically, it admits a non-twisting, non-shearing and non-expanding geodesic null congruence. We calculate all components of the curvature and Ricci tensors, without assuming any specific matter content, and discuss algebraic types and main geometric constraints imposed by general Einstein's field equations. We explicitly derive Einstein-Maxwell equations, including an arbitrary cosmological constant, in the case of vacuum or possibly an aligned electromagnetic field. Finally, we introduce canonical subclasses of the Kundt family and we identify the most important special cases, namely generalised pp-waves, VSI or CSI spacetimes, and gyratons.Comment: 15 page