Testing Connectedness of Images


Berman P. Murzabulatov M. Raskhodnikova S. Ristache D.-F.
November 2024Springer

Algorithmica
2024#86Issue 113496 - 3517 pp.

We investigate algorithms for testing whether an image is connected. Given a proximity parameter ϵ∈(0,1) and query access to a black-and-white image represented by an n×n matrix of Boolean pixel values, a (1-sided error) connectedness tester accepts if the image is connected and rejects with probability at least 2/3 if the image is ϵ-far from connected. We show that connectedness can be tested nonadaptively with O(1ϵ2) queries and adaptively with O(1ϵ3/2log1ϵ) queries. The best connectedness tester to date, by Berman, Raskhodnikova, and Yaroslavtsev (STOC 2014) had query complexity O(1ϵ2log1ϵ) and was adaptive. We also prove that every nonadaptive, 1-sided error tester for connectedness must make Ω(1ϵlog1ϵ) queries.

Computational geometry , Property testing , Sublinear algorithms

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Nazarbayev University, Astana, Kazakhstan
Boston University, Boston, United States

Nazarbayev University
Boston University

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