Nonlinear rank-one modification of the symmetric eigenvalue problem arises from eigenvibrations of mechanical structures with elastically attached loads and calculation of the propagation modes in optical fiber. In this paper, we first study the existence and uniqueness of eigenvalues, and then investigate three numerical algorithms, namely Picard iteration, nonlinear Rayleigh quotient iteratio...

Picard Lattices of Families of K3 Surfaces bysarah-marie belcastro Chair: Igor Dolgachev It is a nontrivial problem to determine the Picard Lattice of a given surface; theobject of this thesis is to compute the Picard Lattices of M. Reid’s list of 95 fami-lies of Gorenstein K3 surfaces which occur as hypersurfaces in weighted projectivespace. Reid’s list arises in many problems;...

We prove a geometric logarithmic derivative lemma for rigid analytic mappings to algebraic varieties in characteristic zero. We use the lemma to give a new and simpler proof (at least in characteristic zero) of Berkovich’s little Picard theorem, which says there are no nonconstant rigid analytic maps from the affine line to nonsingular projective curves of positive genus, and of Cherry’s result...

We study the surface S̄ parametrizing cuboids: it is defined by the equations relating the sides, face diagonals and long diagonal of a rectangular box. It is an open problem whether a ‘rational box’ exists, i.e., a rectangular box all of whose sides, face diagonals and long diagonal have (positive) rational length. The question is equivalent to the existence of nontrivial rational points on S̄. ...

Let X be a K3 surface which is intersection of three (i.e. a net P) of quadrics in P. The curve of degenerate quadrics has degree 6 and defines a natural double covering of P ramified in this curve which is again a K3. This is a classical example of a correspondence between K3 surfaces which is related with moduli of sheaves on K3’s studied by Mukai. When general (for fixed Picard lattices) X a...

A long-standing question in the theory of rational points of algebraic surfaces is whether a K3 surface X over a number field K acquires a Zariski-dense set of L-rational points over some finite extension L/K. In this case, we say X has potential density of rational points. In case XC has Picard rank greater than 1, Bogomolov and Tschinkel [2] have shown in many cases that X has potential densi...

Orders on surfaces provide a rich source of examples of noncommutative surfaces. In [HS05] the authors prove the existence of the analogue of the Picard scheme for orders and in [CK11] the Picard scheme is explicitly computed for an order on P2 ramified on a smooth quartic. In this paper, we continue this line of work, by studying the Picard and Hilbert schemes for an order on P2 ramified on a ...

Let X be a K3 surface which is intersection of three (a net P) of quadrics in P. The curve of degenerate quadrics has degree 6 and defines a double covering of P K3 surface Y ramified in this curve. This is the classical example of a correspondence between K3 surfaces which is related with moduli of vector bundles on K3 studied by Mukai. When general (for fixed Picard lattices) X and Y are isom...

We give model-theoretic accounts and proofs of the following results: Suppose ∂y = Ay is a linear differential equation over a differential field K of characteristic 0, and the field CK of constants of K is existentially closed in K. Then: (i) There exists a Picard-Vessiot extension L of K, namely a differential field extension L of K which is generated by a fundamental system of solutions of t...

Smooth complex Fano varieties of dimension n form a limited family, so they have only a finite number of possible topological types. However not much is known about their topological invariants in higher dimensions. In particular we consider here the second Betti number b2 of a smooth Fano variety X, which coincides with the Picard number ρX . Recall that a Del Pezzo surface S has ρS ≤ 9. Fano ...