Can smooth graphons in several dimensions be represented by smooth graphons on [0,1]?

A graphon that is defined on [0,1]dand is Hölder(α)continuous for some d⩾2and α∈(0,1]can be represented by a graphon on [0,1]that is Hölder(α/d)continuous. We give examples that show that this reduction in smoothness to α/dis the best possible, for any d and α; for α=1, the example is a dot product...

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Main Authors: Svante Janson, Sofia Olhede
Format: Article
Language:English
Published: Elsevier 2021-11-01
Series:Examples and Counterexamples
Subjects:
Online Access:http://www.sciencedirect.com/science/article/pii/S2666657X21000070
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author Svante Janson
Sofia Olhede
author_facet Svante Janson
Sofia Olhede
author_sort Svante Janson
collection DOAJ
description A graphon that is defined on [0,1]dand is Hölder(α)continuous for some d⩾2and α∈(0,1]can be represented by a graphon on [0,1]that is Hölder(α/d)continuous. We give examples that show that this reduction in smoothness to α/dis the best possible, for any d and α; for α=1, the example is a dot product graphon and shows that the reduction is the best possible even for graphons that are polynomials.A motivation for studying the smoothness of graphon functions is that this represents a key assumption in non-parametric statistical network analysis. Our examples show that making a smoothness assumption in a particular dimension is not equivalent to making it in any other latent dimension.
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spelling doaj.art-c46f048455124791b2b18e3f1412dfea2022-12-21T18:45:30ZengElsevierExamples and Counterexamples2666-657X2021-11-011100011Can smooth graphons in several dimensions be represented by smooth graphons on [0,1]?Svante Janson0Sofia Olhede1Department of Mathematics, Uppsala University, PO Box 480, SE-751 06 Uppsala, Sweden; Corresponding author.Institute of Mathematics, Ecole Polytechnique Fédérale de Lausanne, Lausanne, SwitzerlandA graphon that is defined on [0,1]dand is Hölder(α)continuous for some d⩾2and α∈(0,1]can be represented by a graphon on [0,1]that is Hölder(α/d)continuous. We give examples that show that this reduction in smoothness to α/dis the best possible, for any d and α; for α=1, the example is a dot product graphon and shows that the reduction is the best possible even for graphons that are polynomials.A motivation for studying the smoothness of graphon functions is that this represents a key assumption in non-parametric statistical network analysis. Our examples show that making a smoothness assumption in a particular dimension is not equivalent to making it in any other latent dimension.http://www.sciencedirect.com/science/article/pii/S2666657X21000070GraphonSmooth graphonNon-parametric statistical network inference
spellingShingle Svante Janson
Sofia Olhede
Can smooth graphons in several dimensions be represented by smooth graphons on [0,1]?
Examples and Counterexamples
Graphon
Smooth graphon
Non-parametric statistical network inference
title Can smooth graphons in several dimensions be represented by smooth graphons on [0,1]?
title_full Can smooth graphons in several dimensions be represented by smooth graphons on [0,1]?
title_fullStr Can smooth graphons in several dimensions be represented by smooth graphons on [0,1]?
title_full_unstemmed Can smooth graphons in several dimensions be represented by smooth graphons on [0,1]?
title_short Can smooth graphons in several dimensions be represented by smooth graphons on [0,1]?
title_sort can smooth graphons in several dimensions be represented by smooth graphons on 0 1
topic Graphon
Smooth graphon
Non-parametric statistical network inference
url http://www.sciencedirect.com/science/article/pii/S2666657X21000070
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