3,240 research outputs found
On concentrators and related approximation constants
Pippenger ([Pippenger, 1977]) showed the existence of
-concentrator for each positive integer using a probabilistic
method. We generalize his approach and prove existence of
-concentrator (which is no longer regular, but has fewer
edges). We apply this result to improve the constant of approximation of almost
additive set functions by additive set functions from (established in
[Kalton, Roberts, 1983]) to . We show a more direct connection of the
latter problem to the Whitney type estimate for approximation of continuous
functions on a cube in by linear functions, and improve the
estimate of this Whitney constant from (proved in [Brudnyi, Kalton,
2000]) to
Relativistic three-nucleon calculations within the Bethe-Salpeter approach
The relativistic properties of the three-nucleon system are investigated
using the Faddeev equations within the Bethe-Salpeter approach. The
nucleon-nucleon interaction is chosen in a separable form. The Gauss quadrature
method is used to calculate the integrals. The system of the integral equations
are solving by iterations method. The binding energy and the partial-wave
amplitudes (1S 0 and 3S 1) of the triton are found
- …