Block-Graceful Designs

In this article, we adapt the edge-graceful graph labeling definition into block designs and define a block design V,B with V=v and B=b as block-graceful if there exists a bijection f:B⟶1,2,…,b such that the induced mapping f+:V⟶Zv given by f+x=∑x∈AA∈BfAmod v is a bijection. A quick observation show...

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Main Authors: Dilara Erdemir, Emre Kolotoğlu
Format: Article
Language:English
Published: Wiley 2023-01-01
Series:Journal of Mathematics
Online Access:http://dx.doi.org/10.1155/2023/4959576
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author Dilara Erdemir
Emre Kolotoğlu
author_facet Dilara Erdemir
Emre Kolotoğlu
author_sort Dilara Erdemir
collection DOAJ
description In this article, we adapt the edge-graceful graph labeling definition into block designs and define a block design V,B with V=v and B=b as block-graceful if there exists a bijection f:B⟶1,2,…,b such that the induced mapping f+:V⟶Zv given by f+x=∑x∈AA∈BfAmod v is a bijection. A quick observation shows that every v,b,r,k,λ−BIBD that is generated from a cyclic difference family is block-graceful when v,r=1. As immediate consequences of this observation, we can obtain block-graceful Steiner triple system of order v for all v≡1mod 6 and block-graceful projective geometries, i.e., qd+1−1/q−1,qd−1/q−1,qd−1−1/q−1−BIBDs. In the article, we give a necessary condition and prove some basic results on the existence of block-graceful v,k,λ−BIBDs. We consider the case v≡3mod 6 for Steiner triple systems and give a recursive construction for obtaining block-graceful triple systems from those of smaller order which allows us to get infinite families of block-graceful Steiner triple systems of order v for v≡3mod 6. We also consider affine geometries and prove that for every integer d≥2 and q≥3, where q is an odd prime power or q=4, there exists a block-graceful qd,q,1−BIBD. We make a list of small parameters such that the existence problem of block-graceful labelings is completely solved for all pairwise nonisomorphic BIBDs with these parameters. We complete the article with some open problems and conjectures.
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spelling doaj-art-7a830164595746ee88caed7551e446c32025-02-03T06:42:44ZengWileyJournal of Mathematics2314-47852023-01-01202310.1155/2023/4959576Block-Graceful DesignsDilara Erdemir0Emre Kolotoğlu1Department of MathematicsDepartment of MathematicsIn this article, we adapt the edge-graceful graph labeling definition into block designs and define a block design V,B with V=v and B=b as block-graceful if there exists a bijection f:B⟶1,2,…,b such that the induced mapping f+:V⟶Zv given by f+x=∑x∈AA∈BfAmod v is a bijection. A quick observation shows that every v,b,r,k,λ−BIBD that is generated from a cyclic difference family is block-graceful when v,r=1. As immediate consequences of this observation, we can obtain block-graceful Steiner triple system of order v for all v≡1mod 6 and block-graceful projective geometries, i.e., qd+1−1/q−1,qd−1/q−1,qd−1−1/q−1−BIBDs. In the article, we give a necessary condition and prove some basic results on the existence of block-graceful v,k,λ−BIBDs. We consider the case v≡3mod 6 for Steiner triple systems and give a recursive construction for obtaining block-graceful triple systems from those of smaller order which allows us to get infinite families of block-graceful Steiner triple systems of order v for v≡3mod 6. We also consider affine geometries and prove that for every integer d≥2 and q≥3, where q is an odd prime power or q=4, there exists a block-graceful qd,q,1−BIBD. We make a list of small parameters such that the existence problem of block-graceful labelings is completely solved for all pairwise nonisomorphic BIBDs with these parameters. We complete the article with some open problems and conjectures.http://dx.doi.org/10.1155/2023/4959576
spellingShingle Dilara Erdemir
Emre Kolotoğlu
Block-Graceful Designs
Journal of Mathematics
title Block-Graceful Designs
title_full Block-Graceful Designs
title_fullStr Block-Graceful Designs
title_full_unstemmed Block-Graceful Designs
title_short Block-Graceful Designs
title_sort block graceful designs
url http://dx.doi.org/10.1155/2023/4959576
work_keys_str_mv AT dilaraerdemir blockgracefuldesigns
AT emrekolotoglu blockgracefuldesigns