Slow feature analysis (SFA) is an unsupervised-learning algorithm that extracts slowly varying features from a multi-dimensional time series. A supervised extension to SFA for classification and regression is graph-based SFA (GSFA). GSFA is based on the preservation of similarities, which are specified by a graph structure derived from the labels. It has been shown that hierarchical GSFA (HGSFA...

This paper is devoted to the “Discovery of Slowness.” The archetypical perversely awful algorithm bogo-sort, which is sometimes referred to as Monkey-sort, is analyzed with elementary methods. Moreover, practical experiments are performed.

Abstract. The rate of erosion a landscape depends largely on local gradient and material fluxes. Since both quantities are functions the shape catchment surface, this dependence constitutes mathematical straitjacket, in sense that – subject to simplifying assumptions about process, absent variations external forcing erodibility change surface geometry is solely function geometry. Here we demons...

S U M M A R Y A three-stage inversion scheme for surface wave tomography working with multimode phase dispersion as a function of frequency provides a means of combining a wide range of data in a common framework. The phase average approximation is applied directly to phase slowness and there is no need to invoke perturbation arguments for the interpretation of path-averaged velocity models der...

This study examined phonemic (letters), semantic (animals) and action verbal fluency cues in twenty-four patients with FRDA, and twenty matched healthy control subjects. The Action Fluency Test (AFT) is a newly-developed verbal fluency cue that consists in asking the subject to rapidly generate verbs. Given the high presence of dysarthria and cognitive slowness in FRDA patients, control tasks w...

Traveltime, or geodesic distance, is locally the solution of the eikonal equation of geometric optics. However traveltime between sufficiently distant points is generically multivalued. Finite difference eikonal solvers approximate only the viscosity solution, which is the smallest value of the (multivalued) traveltime (‘‘first arrival time’’). The slowness matching method stitches together loc...