Distance 2-restricted optimal pebbling in cycles

Let $ G $ be a graph and let $ \delta $ be a distribution of pebbles on $ G $. A pebbling move on the graph $ G $ consists of removing two pebbles from one vertex and then placing one pebble at an adjacent vertex. Given a positive integer $ d $, if we can move pebbles to any target vertex $ v $ in $...

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Main Authors: Chin-Lin Shiue, Tzu-Hsien Kwong
Format: Article
Language:English
Published: AIMS Press 2025-02-01
Series:AIMS Mathematics
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Online Access:https://www.aimspress.com/article/doi/10.3934/math.2025201
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author Chin-Lin Shiue
Tzu-Hsien Kwong
author_facet Chin-Lin Shiue
Tzu-Hsien Kwong
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description Let $ G $ be a graph and let $ \delta $ be a distribution of pebbles on $ G $. A pebbling move on the graph $ G $ consists of removing two pebbles from one vertex and then placing one pebble at an adjacent vertex. Given a positive integer $ d $, if we can move pebbles to any target vertex $ v $ in $ G $ only from the vertices in the set $ N_d[v] = \{u\in V(G):d(u, v)\le d\} $ by pebbling moves, where $ d(u, v) $ is the distance between $ u $ and $ v $, then such a graph pebbling played on $ G $ is said to be distance $ d $-restricted. For each target vertex $ v\in V(G) $, we use $ m(\delta, d, v) $ to denote the maximum number of pebbles that can be moved to $ v $ only from the vertices in the set $ N_d[v] $. If $ m(\delta, d, v)\ge t $ for each $ v\in V(G) $, then we say that $ \delta $ is $ (d, t) $-solvable. The optimal $ (d, t) $-pebbling number of $ G $, denoted by $ \pi^*_{(d, t)}(G) $, is the minimum number of pebbles needed so that there is a $ (d, t) $-solvable distribution of $ G $. In this article, we study distance $ 2 $-restricted pebbling in cycles and show that for any $ n $-cycle $ C_n $ with $ n\ge 6 $, $ \pi^*_{(2, t)}(C_n) = \pi^*_{(2, t-10)}(C_n)+4n $ for $ t \ge 13 $. It follows that if $ n\ge 6 $, then $ \pi^*_{(2, 10k+r)}(C_n) = \pi^*_{(2, r)}(C_n)+4kn $ for $ k\ge 1 $ and $ 3 \le r \le 12 $. Consequently, for $ n\ge 6 $, the problem of determining the exact value of $ \pi^*_{(2, t)}(C_n) $ for all $ t\ge 1 $ can be reduced to the problem of determining the exact value of $ \pi^*_{(2, r)}(C_n) $ for $ r\in[1, 12] $. We also consider $ C_n $ with $ 3\le n \le 5 $. When $ n = 3 $, we have $ \pi^*_{(2, t)}(C_3) = \pi^*_{(1, t)}(C_3) $, since the diameter of $ C_3 $ is one. The exact value of $ \pi^*_{(1, t)}(C_3) $ is known. When $ n = 4, 5 $, we determine the exact value of $ \pi^*_{(2, t)}(C_n) $ for $ t\ge 1 $.
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spelling doaj-art-61c013bcf2da43f8ae2ac7bc3395bc312025-08-20T02:26:19ZengAIMS PressAIMS Mathematics2473-69882025-02-011024355437310.3934/math.2025201Distance 2-restricted optimal pebbling in cyclesChin-Lin Shiue0Tzu-Hsien Kwong1Department of Applied Mathematics, Chung Yuan Christian University, No. 200, Zhongbei Rd., Zhongli Dist., Taoyuan City 320314, TaiwanDepartment of Applied Mathematics, Chung Yuan Christian University, No. 200, Zhongbei Rd., Zhongli Dist., Taoyuan City 320314, TaiwanLet $ G $ be a graph and let $ \delta $ be a distribution of pebbles on $ G $. A pebbling move on the graph $ G $ consists of removing two pebbles from one vertex and then placing one pebble at an adjacent vertex. Given a positive integer $ d $, if we can move pebbles to any target vertex $ v $ in $ G $ only from the vertices in the set $ N_d[v] = \{u\in V(G):d(u, v)\le d\} $ by pebbling moves, where $ d(u, v) $ is the distance between $ u $ and $ v $, then such a graph pebbling played on $ G $ is said to be distance $ d $-restricted. For each target vertex $ v\in V(G) $, we use $ m(\delta, d, v) $ to denote the maximum number of pebbles that can be moved to $ v $ only from the vertices in the set $ N_d[v] $. If $ m(\delta, d, v)\ge t $ for each $ v\in V(G) $, then we say that $ \delta $ is $ (d, t) $-solvable. The optimal $ (d, t) $-pebbling number of $ G $, denoted by $ \pi^*_{(d, t)}(G) $, is the minimum number of pebbles needed so that there is a $ (d, t) $-solvable distribution of $ G $. In this article, we study distance $ 2 $-restricted pebbling in cycles and show that for any $ n $-cycle $ C_n $ with $ n\ge 6 $, $ \pi^*_{(2, t)}(C_n) = \pi^*_{(2, t-10)}(C_n)+4n $ for $ t \ge 13 $. It follows that if $ n\ge 6 $, then $ \pi^*_{(2, 10k+r)}(C_n) = \pi^*_{(2, r)}(C_n)+4kn $ for $ k\ge 1 $ and $ 3 \le r \le 12 $. Consequently, for $ n\ge 6 $, the problem of determining the exact value of $ \pi^*_{(2, t)}(C_n) $ for all $ t\ge 1 $ can be reduced to the problem of determining the exact value of $ \pi^*_{(2, r)}(C_n) $ for $ r\in[1, 12] $. We also consider $ C_n $ with $ 3\le n \le 5 $. When $ n = 3 $, we have $ \pi^*_{(2, t)}(C_3) = \pi^*_{(1, t)}(C_3) $, since the diameter of $ C_3 $ is one. The exact value of $ \pi^*_{(1, t)}(C_3) $ is known. When $ n = 4, 5 $, we determine the exact value of $ \pi^*_{(2, t)}(C_n) $ for $ t\ge 1 $.https://www.aimspress.com/article/doi/10.3934/math.2025201graph pebblingoptimal pebblingcapacity-restricted pebblingdistance-restricted pebblingcycle
spellingShingle Chin-Lin Shiue
Tzu-Hsien Kwong
Distance 2-restricted optimal pebbling in cycles
AIMS Mathematics
graph pebbling
optimal pebbling
capacity-restricted pebbling
distance-restricted pebbling
cycle
title Distance 2-restricted optimal pebbling in cycles
title_full Distance 2-restricted optimal pebbling in cycles
title_fullStr Distance 2-restricted optimal pebbling in cycles
title_full_unstemmed Distance 2-restricted optimal pebbling in cycles
title_short Distance 2-restricted optimal pebbling in cycles
title_sort distance 2 restricted optimal pebbling in cycles
topic graph pebbling
optimal pebbling
capacity-restricted pebbling
distance-restricted pebbling
cycle
url https://www.aimspress.com/article/doi/10.3934/math.2025201
work_keys_str_mv AT chinlinshiue distance2restrictedoptimalpebblingincycles
AT tzuhsienkwong distance2restrictedoptimalpebblingincycles