The literature about species concepts might be larger than that about any other subject in evolutionary biology, but the issue of empirically testing species boundaries has been given little attention relative to seemingly endless debates over what species are. The practical issue of delimiting species boundaries is nevertheless of central importance to many areas of evolutionary biology. The n...

ly and Concretely

The four-triangles longest-edge (4T-LE) partition of a triangle t is obtained by joining the midpoint of the longest edge of t to the opposite vertex and to the midpoints of the two remaining edges. The so-called self-improvement property of the refinement algorithm based on the 4-triangles longest-edge partition is discussed and delimited by studying the number of dissimilar triangles arising ...

While the notion of the ‘area’ or ‘Sprachbund’ has a long history in linguistics, with geographically-defined regions frequently cited as a useful means to explain typological distributions, the problem of delimiting areas has not been well addressed. Lists of general purpose largely independent ‘macro-areas’ (typically continent size) have been proposed as a step to rule out contact as an expl...

Closure: Every segment must be delimited by exactly two vertices, and every vertex must be at the intersection of exactly two segments. (Fig. la) No self-intersection: Any two segments can intersect only if they are adjacent, in this case the intersection point is the shared vertex (Fig. lb). Orientation: Every segment must have a direction, and the directions of all the segments must be consis...

In this paper, I provide a notion of domain of application of a scientific theory that is sensitive to various aspects of scientific practice, accommodates central features of the latter without generating relativistic conclusions, while still acknowledging the presence of incommensurability. To articulate the proposal, scientific instruments will play a central role. In the end, these instrume...

Abstract Finding word boundaries in continuous speech is challenging as there little or no equivalent of a ‘space’ delimiter between words. Popular Bayesian non-parametric models for text segmentation (Goldwater et al., 2006, 2009) use Dirichlet process to jointly segment sentences and build lexicon types. We introduce DP-Parse, which uses similar principles but only relies on an instance token...

The proportion of exotic species (the exotic fraction) on islands has been reported to be almost three times that of mainland sites of similar size (Lonsdale, 1999). The disproportionately larger fraction of exotic species has been cited as indicating that islands are highly vulnerable to invasion (Elton, 1958; but see Bellemain & Ricklefs, 2008). Although the generality of this claim has been ...

This paper describes formal bases for designing a PostScript dynamic font respecting some basic rules of Arabic calligraphy. This font will provide, for instance, a vertical curvilinear characters dynamic stretching that depends on their horizontal stretching according to the Calligraphic rules. Vertical and horizontal ligatures will also be supported by the proposed font. The techniques used c...