Thesis (doctoral)--Friedrich-Wilhelms-Universität zu Berlin, 1884. / Vita.

In this work, several problems in the field of Hamiltonian dynamics are studied. Chapter 1 is a short review of some basic results in the theory of Hamiltonian dynamics. In chapter 2, we study the problem of computing the geometric monodromy of the torus bundle defined by integrable Hamiltonian systems. We show that for two degree of freedom systems near an isolated critical value of the energy momentum map, the monodromy group can be determined solely from the local data of the energy momentum map at the singularity. Along the way, we develop a simple method for computing the monodromy group which covers all the known examples that exhibit nontrivial monodromy. In chapter 3, we consider the topological aspects of the Kirchhoff case of the motion of a symmetric rigid body in an infinite ideal fluid. The bifurcation diagrams are constructed and the topology of all the invariant sets are determined. We show that this system has monodromy. We show also that this system undergoes a Hamiltonian Hopf bifurcation as the couple resultant passes through a certain value when the steady rotation of the rigid body about its symmetry axis changes stability. Chapter 4 is devoted to checking Kolmogorov's condition for the square potential pendulum. We prove, by essentially elementary methods, that Kolmogorov's condition is satisfied for all of the regular values of the energy momentum map. In chapter 5, we use Ziglin's theorem to prove rigorously that some of the generalized two degree of freedom Toda lattices are non-integrable.

The main object of study is the theory of Schrödinger operators with meromorphic potentials, having trivial monodromy in the complex domain. In the first part we study the spectral properties of a class of such operators related to the classical Whittaker-Hill equation (-d^2/dx^2+Acos2x+Bcos4x)Ψ=λΨ. The equation, for special choices of A and B, is known to have the remarkable property that half of the gaps eventually become closed (semifinite-gap operator). Using the Darboux transformation we construct new trigonometric examples of semifinite-gap operators with real, smooth potentials. A similar technique applied to the Lamé operator gives smooth, real, finite-gap potentials in terms of classical Jacobi elliptic functions. In the second part we study the singular locus of monodromy-free potentials in the complex domain. A particular case is given by the zeros of Wronskians of Hermite polynomials, which are studied in detail. We introduce a class of partitions (doubled partitions) for which we observe a direct qualitative relationship between the pattern of zeros and the shape of the corresponding Young diagram. For the Wronskians W(H_n,H_{n+k}) we give an asymptotic formula for the curve on which zeros lie as n → ∞. We also give some empirical formulas for asymptotic behaviour of zeros of Wronskians of 3 and 4 Hermite polynomials. In the last chapter we apply the theory of monodromy-free operators to produce new vortex equilibria in the periodic case and in the presence of background flow.

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In this thesis, we study the compatibility between local and global Langlands correspondences for \(GL_n\). This generalizes the compatibility between local and global class field theory and is related to deep conjectures in algebraic geometry and harmonic analysis, such as the Ramanujan-Petersson conjecture and the weight monodromy conjecture. Let L be a CM field. We consider the case when \(\Pi\) is a cuspidal automorphic representation of \(GL_n(\mathbb{A}_L^\infty)\), which is conjugate self-dual and regular algebraic. Under these assumptions, there is an l-adic Galois representation \(R_l(\Pi)\) associated to \(\Pi\), which is known to be compatible with the local Langlands correspondence in most cases (for example, when n is odd) and up to semisimplification in general. In this thesis, we complete the proof of the compatibility when \(l \neq p\) by identifying the monodromy operator N on both the local and the global sides. On the local side, the identification amounts to proving the Ramanujan-Petersson conjecture for \(\Pi\) as above. On the global side it amounts to proving the weight-monodromy conjecture for part of the cohomology of a certain Shimura variety. / Mathematics

Univ., Diss.--Sendai.

Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references. Available also from UMI Company.

One of the most important tools to study the geometry of irreducible holomorphic symplectic manifolds is the monodromy group. The first part of this dissertation concerns the construction and studyof monodromy operators on irreducible holomorphic symplectic manifolds which are deformation equivalent to the 10-dimensional example constructed by O'Grady. The second part uses the knowledge of the monodromy group to compute the number of connected components of moduli spaces of bothmarked and polarised irreducible holomorphic symplectic manifolds which are deformationequivalent to generalised Kummer varieties.

Em 1968, J. Milnor introduziu a monodromia local de Picard-Lefschetz de uma hipersuperfície complexa com singularidade isolada. Em seguida, E. Brieskorn perguntou se esta monodromia é sempre finita. Em 1972, Lê Dúng Trâng provou que a resposta é positiva no caso de germes de curvas planas analíticas irredutíveis. Na época, já eram conhecidos exemplos de curvas planas com dois ramos e monodromia finita. Em 1973, N. A?Campo produziu o primeiro exemplo de germe de curva plana com dois ramos e monodromia infinita. Portanto, a questão mais simples, e ainda em aberto, que se coloca neste contexto, é a determinação da finitude da monodromia para germes de curvas planas com dois ramos. O presente trabalho, consiste em determinar, em várias situações, o polinômio mínimo da monodromia de germes de curvas analíticas planas com dois ramos, cujos gêneros são menores ou iguais a dois, o que permite decidir a sua finitude / In 1968, J. Milnor introduced the Picard-Lefschetz monodromy of a complex hypersurface with an isolated singularity. Subsequently, E. Brieskorn asked if this monodromy is always finite. In 1972, Lê Dúng Trâng proved that the answer is positive in the case of irreducible analytic germs of plane curves. At this time, examples of plane curves with two branches and finite monodromy were known. In 1973, N. A?Campo produced the first example of a germ of plane curve with two branches and infinite monodromy. Therefore, the simplest and still open problem in this context is to determine whether the monodromy of a plane curve with two branches is finite or infinite. The present work consists in determining, in several situations, the minimal polynomial of the monodromy for germs of plane analytic curves with two branches, whose genera are less or equal than two, wich allows us to decide its finiteness

Em 1968, J. Milnor introduziu a monodromia local de Picard-Lefschetz de uma hipersuperfície complexa com singularidade isolada. Em seguida, E. Brieskorn perguntou se esta monodromia é sempre finita. Em 1972, Lê Dúng Trâng provou que a resposta é positiva no caso de germes de curvas planas analíticas irredutíveis. Na época, já eram conhecidos exemplos de curvas planas com dois ramos e monodromia finita. Em 1973, N. A?Campo produziu o primeiro exemplo de germe de curva plana com dois ramos e monodromia infinita. Portanto, a questão mais simples, e ainda em aberto, que se coloca neste contexto, é a determinação da finitude da monodromia para germes de curvas planas com dois ramos. O presente trabalho, consiste em determinar, em várias situações, o polinômio mínimo da monodromia de germes de curvas analíticas planas com dois ramos, cujos gêneros são menores ou iguais a dois, o que permite decidir a sua finitude / In 1968, J. Milnor introduced the Picard-Lefschetz monodromy of a complex hypersurface with an isolated singularity. Subsequently, E. Brieskorn asked if this monodromy is always finite. In 1972, Lê Dúng Trâng proved that the answer is positive in the case of irreducible analytic germs of plane curves. At this time, examples of plane curves with two branches and finite monodromy were known. In 1973, N. A?Campo produced the first example of a germ of plane curve with two branches and infinite monodromy. Therefore, the simplest and still open problem in this context is to determine whether the monodromy of a plane curve with two branches is finite or infinite. The present work consists in determining, in several situations, the minimal polynomial of the monodromy for germs of plane analytic curves with two branches, whose genera are less or equal than two, wich allows us to decide its finiteness