1. introduction the analysis of drainage networks is a powerful tool to detect recent tectonic activity and uplift, as river channels are very sensitive to changes in the parameters that control their shapes and. climate changes, tectonics and lithology affect river equilibrium conditions and hence, river geometry. a river is in dynamic equilibrium when erosion keeps pace with sedimentation and...

This is the text of lectures delivered at the RIMS (Kyoto University) in July 1998. It presents the basic structures of the theory of noncommutative symmetric functions, with emphasis on the parallel with the commutative theory and on the representation theoretical interpretations. Some examples involving descent algebras and characters of symmetric groups are discussed in detail. Introduction ...

This work deals with the H1 condition numbers and the distribution of the ~ N;Msingular values of the preconditioned operators f~ 1 N;M WN;M ÂN;Mg. ÂN;M is the matrix representation of the Legendre Spectral Collocation discretization of the elliptic operator A de ned by Au := u + a1ux + a2uy + a0u in (the unit square) with boundary conditions: u = 0 on 0; @u @ A = u on 1. ~ N;M is the sti ness ...