Function values as boundary integrals

Function Values as Boundary Integrals

Boundary Values of Cauchy Type Integrals

Results by A. G. Poltoratskĭı and A. B. Aleksandrov about nontangential boundary values of pseudocontinuable H2-functions on sets of zero Lebesgue measure are used for the study of operators on L2-spaces on the unit circle. For an arbitrary bounded operator X acting from one such L2-space to another and having the property that the commutator of it with multiplication by the independent variabl...

Euler-type Multiple Integrals as Linear Forms in Zeta Values

0. In 1978, Apéry showed the irrationality of ζ(3) = ∑∞ n=1 1 n3 by giving the approximants `n = unζ(3) − vn ∈ Qζ(3) + Q, un, dnvn ∈ Z, dn = l.c.m.(1, 2, . . . , n), with the property |`n| → ( √ 2 − 1) < 1/e as n → ∞. A similar approach was put forward to show the irrationality of ζ(2) (which is π/6, hence transcendental thanks to Lindemann) but I will concentrate on the case of ζ(3). A few mon...

Path integrals and boundary conditions

The path integral approach to quantum mechanics provides a method of quantization of dynamical systems directly from the Lagrange formalism. In field theory the method presents some advantages over Hamiltonian quantization. The Lagrange formalism preserves relativistic covariance which makes the Feynman method very convenient to achieve the renormalization of field theories both in perturbative...

Approximation of Integrals for Boundary Element Methods

A new method for approximating two-dimensional integrals B f (x) µ(dx) over surfaces B ⊂ R 3 is introduced where µ is the standard measure of surface area. Such integrals typically occur in boundary element methods. The algorithm is based on triangulations T := T i approximating B. Under the assumption that the surface B is given implicitly by an equation H(x) = 0, a retraction P : U ⊃ B → B is...