Browsing 1  Oberwolfach Preprints (OWP) by MSC "65"
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Discretization of Inherent ODEs and the Geometric Integration of DAEs with Symmetries
[OWP202210] (Mathematisches Forschungsinstitut Oberwolfach, 20220608)Discretization methods for differentialalgebraic equations (DAEs) are considered that are based on the integration of an associated inherent ordinary differential equation (ODE). This allows to make use of any discretization ... 
A Gentle Introduction to Interpolation on the Grassmann Manifold
[OWP202402] (Mathematisches Forschungsinstitut Oberwolfach, 20240110) 
Local and Global Canonical Forms for DifferentialAlgebraic Equations with Symmetries
[OWP202205] (Mathematisches Forschungsinstitut Oberwolfach, 20220221)Linear timevarying differentialalgebraic equations with symmetries are studied. The structures that we address are selfadjoint and skewadjoint systems. Local and global canonical forms under congruence are presented ... 
Low rank differential equations for hamiltonian matrix nearness problems
[OWP201301] (Mathematisches Forschungsinstitut Oberwolfach, 20130208)For a Hamiltonian matrix with purely imaginary eigenvalues, we aim to determine the nearest Hamiltonian matrix such that so me or all eigenvalues leave the imaginary axis. Conversely, for a Hamiltonian matrix with all ... 
Mesh Ratios for BestPacking and Limits of Minimal Energy Configurations
[OWP201313] (Mathematisches Forschungsinstitut Oberwolfach, 20130610)For $N$point bestpacking configurations $\omega_N$ on a compact metric space $(A, \rho)$, we obtain estimates for the meshseparation ratio $\gamma(\rho_N , A)$, which is the quotient of the covering radius of $\omega_N$ ... 
MultiDimensional SummationbyParts Operators for General Function Spaces: Theory and Construction
[OWP202313] (Mathematisches Forschungsinstitut Oberwolfach, 20230725)Summationbyparts (SBP) operators allow us to systematically develop energystable and highorder accurate numerical methods for timedependent differential equations. Until recently, the main idea behind existing SBP ... 
Nonstationary multivariate subdivision: joint spectral radius and asymptotic similarity
[OWP201320] (Mathematisches Forschungsinstitut Oberwolfach, 20131029)In this paper we study scalar multivariate nonstationary subdivision schemes with a general integer dilation matrix. We present a new numerically efficient method for checking convergence and Hölder ... 
On Dykstra’s Algorithm with Bregman Projections
[OWP202404] (Mathematisches Forschungsinstitut Oberwolfach, 20240416)We provide quantitative results on the asymptotic behavior of Dykstra’s algorithm with Bregman projections, a combination of the wellknown Dykstra’s algorithm and the method of cyclic Bregman projections, designed to find ... 
A real algebra perspective on multivariate tight wavelet frames
[OWP201211] (Mathematisches Forschungsinstitut Oberwolfach, 20120813)Recent results from real algebraic geometry and the theory of polynomial optimization are related in a new framework to the existence question of multivariate tight wavelet frames whose generators have at least one vanishing ... 
Review of the Methods of Reflections
[OWP201727] (Mathematisches Forschungsinstitut Oberwolfach, 20171018)The methods of reflections were invented to obtain approximate solutions of the motion of more than one particle in a given environment, provided that one can represent the solution for one particle rather easily. This ... 
Selfadjoint differentialalgebraic equations
[OWP201127] (Mathematisches Forschungsinstitut Oberwolfach, 20110524)Motivated from linearquadratic optimal control problems for differentialalgebraic equations (DAEs), we study the functional analytic properties of the operator associated with the necessary optimality boundary value ... 
Simulation of Multibody Systems with Servo Constraints through Optimal Control
[OWP201518] (Mathematisches Forschungsinstitut Oberwolfach, 2015)We consider mechanical systems where the dynamics are partially constrained to prescribed trajectories. An example for such a system is a building crane with a load and the requirement that the load moves on a certain path. ... 
Supertropical Matrix Algebra III : Powers of Matrices and Generalized Eigenspaces
[OWP201020] (Mathematisches Forschungsinstitut Oberwolfach, 2010)We investigate powers of supertropical matrices, with special attention to the role of the coefficients of the supertropical characteristic polynomial (especially the supertropical trace) in controlling the rank of a power ... 
Theoretical Analysis and Simulation Methods for Hawkes Processes and their Diffusion Approximation
[OWP202009] (Mathematisches Forschungsinstitut Oberwolfach, 20200330)Oscillatory systems of interacting Hawkes processes with Erlang memory kernels were introduced in Ditlevsen and Löcherbach (2017). They are piecewise deterministic Markov processes (PDMP) and can be approximated by a ... 
Time Discretization Schemes for Hyperbolic Systems on Networks by εExpansion
[OWP201903] (Mathematisches Forschungsinstitut Oberwolfach, 20190212)We consider partial differential equations on networks with a small parameter $\epsilon$, which are hyperbolic for $\epsilon>0$ and parabolic for $\epsilon=0$. With a combination of an $\epsilon$expansion and RungeKutta ... 
Weakduality based adaptive finite element methods for PDEconstrained optimization with pointwise gradient stateconstraints
[OWP201015] (Mathematisches Forschungsinstitut Oberwolfach, 2010)Adaptive finite element methods for optimization problems for second order linear elliptic partial di erential equations subject to pointwise constraints on the $\ell^2$norm of the gradient of the state are considered. ... 
Yet another algorithm for the symmetric eigenvalue problem
[OWP201602] (Mathematisches Forschungsinstitut Oberwolfach, 20160510)In this paper we present a new algorithm for solving the symmetric matrix eigenvalue problem that works by first using a Cayley transformation to convert the symmetric matrix into a unitary one and then uses Gragg’s ...