Text Line Segmentation of Historical Documents: a Survey

There is a huge amount of historical documents in libraries and in various National Archives that have not been exploited electronically. Although automatic reading of complete pages remains, in most cases, a long-term objective, tasks such as word spotting, text/image alignment, authentication and extraction of specific fields are in use today. For all these tasks, a major step is document segmentation into text lines. Because of the low quality and the complexity of these documents (background noise, artifacts due to aging, interfering lines),automatic text line segmentation remains an open research field. The objective of this paper is to present a survey of existing methods, developed during the last decade, and dedicated to documents of historical interest.Comment: 25 pages, submitted version, To appear in International Journal on Document Analysis and Recognition, On line version available at http://www.springerlink.com/content/k2813176280456k3

Bounds on the dimension of linear series on stable curves

We study the dimension of linear series on stable curves. In the first part, we show that a general linear series with semistable multidegree is not special, and obtain results on the dimension of the special loci in the Picard scheme. In the process, we give a new characterization of semistability when the total degree equals the genus of the curve. In the second part, we give a generalization of Clifford's inequality to linear series of uniform multidegree and show that the new bound is achieved on every stable curve.Comment: 23 pages, 4 Figure

Coning-off CAT(0) cube complexes

In this paper, we study the geometry of cone-offs of CAT(0) cube complexes over a family of combinatorially convex subcomplexes, with an emphasis on their Gromov-hyperbolicity. A first application gives a direct cubical proof of the characterization of the (strong) relative hyperbolicity of right-angled Coxeter groups, which is a particular case of a result due to Behrstock, Caprace and Hagen. A second application gives the acylindrical hyperbolicity of $C'(1/4)-T(4)$ small cancellation quotients of free products.Comment: 45 pages, 13 figures. Comments are welcom