Towards a Digital Homotopy Theory

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Gregory Lupton, Cleveland State University

I will present a progress report on some work joint with John Oprea and Nick Scoville. 听An n-dimensional digital image is a finite subset of the integer lattice in R^n, together with an adjacency relation. 听For instance, a 2-dimensional digital image is an abstraction of an actual digital image consisting of pixels. 听Our work consists of developing notions and techniques from homotopy theory in the setting of digital images. 听

In an extensive literature, 听a number of authors have introduced concepts from topology into the study of digital images. 听 But some of these notions, as they appear in the literature, do not seem satisfactory from a homotopy point of view. 听Indeed, some of the constructs most useful in homotopy theory, such as cofibrations and path spaces, are absent from the literature. 听Working in the digital setting, we develop some basic ideas of homotopy theory, including cofibrations and path fibrations, in a way that seems more suited to homotopy theory. 听I will indicate how our approach may be used, for example, to study Lusternik-Schnirelmann category in a digital setting. 听One future goal is to develop a characterization of a "homotopy circle" (in the digital setting) using the notion of topological complexity. 听This is with a view towards recognizing circles, and perhaps other features, using these ideas. 听This talk will introduce some听of the basics of topological notions in the setting of digital images, and will not require any specialized background.