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Extension of continuous functions in digital spaces with the Khalimsky topology
Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics.
2005 In: Topology Appl., Vol. 153, 52–65- p.Article in journal (Refereed) Published
Place, publisher, year, edition, pages
2005. Vol. 153, 52–65- p.
URN: urn:nbn:se:uu:diva-96673OAI: oai:DiVA.org:uu-96673DiVA: diva2:171324
Available from: 2008-02-05 Created: 2008-02-05Bibliographically approved
In thesis
1. Digital Geometry and Khalimsky Spaces
Open this publication in new window or tab >>Digital Geometry and Khalimsky Spaces
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[sv]
Digital Geometri och Khalimskyrum
Abstract [en]

Digital geometry is the geometry of digital images. Compared to Euclid’s geometry, which has been studied for more than two thousand years, this field is very young.

Efim Khalimsky’s topology on the integers, invented in the 1970s, is a digital counterpart of the Euclidean topology on the real line. The Khalimsky topology became widely known to researchers in digital geometry and computer imagery during the early 1990s.

Suppose that a continuous function is defined on a subspace of an n-dimensional Khalimsky space. One question to ask is whether this function can be extended to a continuous function defined on the whole space. We solve this problem. A related problem is to characterize the subspaces on which every continuous function can be extended. Also this problem is solved.

We generalize and solve the extension problem for integer-valued, Khalimsky-continuous functions defined on arbitrary smallest-neighborhood spaces, also called Alexandrov spaces.

The notion of a digital straight line was clarified in 1974 by Azriel Rosenfeld. We introduce another type of digital straight line, a line that respects the Khalimsky topology in the sense that a line is a topological embedding of the Khalimsky line into the Khalimsky plane.

In higher dimensions, we generalize this construction to digital Khalimsky hyperplanes, surfaces and curves by digitization of real objects. In particular we study approximation properties and topological separation properties.

The last paper is about Khalimsky manifolds, spaces that are locally homeomorphic to n-dimensional Khalimsky space. We study different definitions and address basic questions such as uniqueness of dimension and existence of certain manifolds.

Place, publisher, year, edition, pages
Uppsala: Matematiska institutionen, 2008. vii+47 p.
Uppsala Dissertations in Mathematics, ISSN 1401-2049 ; 54
Applied mathematics, Khalimsky topology, digital geometry, digital topology, Alexandrov space, digital surface, digital curve, digital manifold, continuous extension, smallest-neighborhood space, image processing, Tillämpad matematik
urn:nbn:se:uu:diva-8419 (URN)978-91-506-1983-6 (ISBN)
Public defence
2008-02-29, Häggsalen, Ångström Laboratory, 13:15
Available from: 2008-02-05 Created: 2008-02-05Bibliographically approved

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