H-V-Super-Strong-(a,d)-antimagic decomposition of complete bipartite graphs

Solomon Stalin Kumar1
1Department of Mathematics, The American College, Madurai – 625 002, Tamilnadu, India.

Abstract

An H-(a,d)-antimagic labeling in a H-decomposable graph G is a bijection f:V(G)E(G){1,2,,p+q} such that f(H1),f(H2),,f(Hh) forms an arithmetic progression with difference d and first element a. f is said to be H-V-super-(a,d)-antimagic if f(V(G))={1,2,,p}. Suppose that V(G)=U(G)W(G) with |U(G)|=m and |W(G)|=n. Then f is said to be H-V-super-strong-(a,d)-antimagic labeling if f(U(G))={1,2,,m} and f(W(G))={m+1,m+2,,(m+n=p)}. A graph that admits a H-V-super-strong-(a,d)-antimagic labeling is called a H-V-super-strong-(a,d)-antimagic decomposable graph. In this paper, we prove that complete bipartite graphs Km,n are H-V-super-strong-(a,d)-antimagic decomposable with both m and n are even.

Keywords: H-decomposable graph, H-V-super magic labeling, Complete bipartite graph

1. Introduction

In this paper we consider only finite and simple undirected bipartite graphs. The vertex and edge sets of a graph G are denoted by V(G) and E(G) respectively and we let |V(G)|=p and |E(G)|=q. For graph theoretic notations, we follow [1, 2]. A labeling of a graph G is a mapping that carries a set of graph elements, usually vertices and/or edges into a set of numbers, usually integers. Many kinds of labeling have been studied and an excellent survey of graph labeling can be found in[3].

Although magic labeling of graphs was introduced by Sedlacek [4], the concept of vertex magic total labeling (VMTL) first appeared in 2002 in[5]. In 2004, MacDougall et al. [6] introduced the notion of super vertex magic total labeling (SVMTL). In 1998, Enomoto et al. [7] introduced the concept of super edge-magic graphs. In 2005, Sugeng and Xie[8] constructed some super edge-magic total graphs. The usage of the word “super” was introduced in[7]. The notion of a V-super vertex magic labeling was introduced by MacDougall et al.[6] as in the name of super vertex-magic total labeling and it was renamed as V-super vertex magic labeling by Marr and Wallis in [9] after referencing the article[10]. Most recently, Tao-ming Wang and Guang-Hui Zhang [11], generalized some results found in [10].

Hartsfield and Ringel [12] introduced the concept of an antimagic graph. In their terminology, an antimagic labeling is an edge-labeling of the graph with the integers 1,2,,q so that the weight at each vertex is different from the weight at any other vertex. Bodendiek and Walther [13] defined the concept of an (a,d)-antimagic labeling as an edge-labeling in which the vertex weights forms an arithmetic progression starting from a and having common difference d. Baˇca et al.[14] introduced the notions of vertex-antimagic total labeling and (a,d)-vertex-antimagic total labeling. Simanjuntak et al [15] introduced the concept of (a,d)-antimagic graph. Sudarasana et al [16] studied the concept of super edge-antimagic total lableing of disconnected graphs.

A bijection f from V(G)E(G) to the integers 1,2,,p+q is called a vertex-antimagic total labeling of G if the weights of vertices {wf(x)=f(x)+xyE(G)f(xy), xV(G)}, are pairwise distinct. f is called an (a,d)-vertex-antimagic total labeling of G if the set of vertex weights {wf(x)|xV(G)}={a,a+d,,a+(p1)d} for some integers a and d. f is said to be super-(a,d)-vertex-antimagic labeling if f(V(G))={1,2,,p}. A graph G is called super-(a,d)-vertex-antimagic if it admits a super-(a,d)-vertex-antimagic labeling. A bijection f from V(G)E(G) to the integers 1,2,,p+q is called an (a,d)-edge-antimagic total labeling of G if the edge weights {w(uv)=f(u)+f(v)+f(uv), uvE(G)}, forms an arithmetic sequence with the first term a and common difference d. f is said to be super-(a,d)-edge-antimagic labeling if f(V(G))={1,2,,p}. A graph G is called super-(a,d)-edge-antimagic if it admits a super-(a,d)-edge-antimagic labeling.

A covering of G is a family of subgraphs H1,H2,,Hh such that each edge of E(G) belongs to at least one of the subgraphs Hi, 1ih. Then it is said that G admits an (H1,H2,,Hh) covering. If every Hi is isomorphic to a given graph H, then G admits an H-covering. A family of subgraphs H1,H2,,Hh of G is a H-decomposition of G if all the subgraphs are isomorphic to a graph H, E(Hi)E(Hj)= for ij and i=1hE(Hi)=E(G). In this case, we write G=H1H2Hh and G is said to be H-decomposable.

The notion of H-super magic labeling was first introduced and studied by Gutie´rrez and Llado´[17] in 2005. They proved that some classes of connected graphs are H-super magic. Suppose G is H-decomposable. A total labeling f:V(G)E(G){1,2,,p+q} is called an H-magic labeling of G if there exists a positive integer k (called magic constant) such that for every copy H in the decomposition, vV(H)f(v)+eE(H)f(e)=k. A graph G that admits such a labeling is called a H-magic decomposable graph. An H-magic labeling f is called a HV-super magic labeling if f(V(G))={1,2,,p}. A graph that admits a HV-super magic labeling is called a HV-super magic decomposable graph. An H-magic labeling f is called a HE-super magic labeling if f(E(G))={1,2,,q}. A graph that admits a HE-super magic labeling is called a HE-super magic decomposable graph. The sum of all vertex and edge labels on H is denoted by f(H).

In 2001, Muntaner-Batle[18] introduced the concept of super-strong magic labeling of bipartite graph as in the name of special super magic labeling of bipartite graph and it was renamed as super-strong magic labeling by Marr and Wallis[9]. Marimuthu and Stalin Kumar [19] introduced the concept of HV-super-strong magic decomposition and HE-super-strong magic decomposition of complete bipartite graphs. Suppose G is a bipartite graph with vertex-sets V1 and V2 of sizes m and n respectively. An edge-magic total labeling of G is super-strong if the elements of V1 receive labels {1,2,,m} and the elements of V2 receive labels {m+1,m+2,,m+n}. Suppose G is H-decomposable and if V(G)=U(G)W(G) with |U(G)|=m and |W(G)|=n. An HV-super magic labeling f is called a HV-super-strong magic if f(U(G))={1,2,,m} and f(W(G))={m+1,m+2,,(m+n=p)}. A graph that admits a HV-super-strong magic labeling is called a HV-super-strong magic decomposable graph. An HE-super magic labeling f is called a HE-super-strong magic labeling if if f(U(G))={q+1,q+2,,q+m} and f(W(G))={q+m+1,q+m+2,,(q+m+n=qp)}. A graph that admits a HE-super-strong magic labeling is called a HE-super-strong magic decomposable graph.

Suppose G is H-decomposable. A total labeling f:V(G)E(G){1,2,,p+q} is called an H-antimagic labeling of G if f(H1),f(H2),,f(Hh) are pairwaise distinct. f is said to be H(a,d)-antimagic if these numbers forms an arithmetic progression with difference d and first element a. A H(a,d)-antimagic labeling f is called HV-super-(a,d)-antimagic labeling if f(V(G))={1,2,,p}. Suppose that V(G)=U(G)W(G) with |U(G)|=m and |W(G)|=n. Then f is said to be HV-super-strong-(a,d)-antimagic labeling if f(U(G))={1,2,,m} and f(W(G))={m+1,m+2,,(m+n=p)}. A graph that admits a HV-super-strong-(a,d)-antimagic labeling is called a HV-super-strong-(a,d)-antimagic decomposable graph. A H(a,d)-antimagic labeling f is called HE-super-(a,d)-antimagic labeling if f(E(G))={1,2,,q}. f is said to be HE-super-strong-(a,d)-antimagic labeling if f(U(G))={q+1,q+2,,q+m} and f(W(G))={q+m+1,q+m+2,,(q+m+n=qp)}. A graph that admits a HE-super-strong-(a,d)-antimagic labeling is called a HE-super-strong-(a,d)-antimagic decomposable graph.

In 2012, Inayah et al. [20] studied magic and anti-magic H-decompositions and Zhihe Liang [21] studied cycle-super magic decompositions of complete multipartite graphs. In many of the results about H-magic graphs, the host graph G is required to be H-decomposable. Yoshimi Ecawa et al [22] studied the decomposition of complete bipartite graphs into edge-disjoint subgraphs with star components. The notion of star-subgraph was introduced by Akiyama and Kano in [23]. A subgraph F of a graph G is called a star-subgraph if each component of F is a star. Here by a star, we mean a complete bipartite graph of the form K1,m with m1. A subgraph F of a graph G is called a n-star-subgraph if FK1,n with 2n<p. Marimuthu and Stalin Kumar [24, 25] studied about the HV-super magic decomposition and HE-super magic decomposition of complete bipartite graphs.

2. Main Results

In this section, we consider the graphs GKm,n and HK1,n, where n1 and both m and n are even. Clearly p=m+n and q=mn.

Theorem 1. Suppose {H1,H2,,Hm} is a n-star-decomposition of G with both m and n are even. Then G is HV-super-strong-(a,d)-antimagic decomposable with a=1+n2(m+3)+2n(2m+1)2 and d=1.

Proof. Let U={u1,u2,,um} and V={v1,v2,,vn} be two stable sets of G. Let {H1,H2,,Hm} be a n-star decomposition of G with both m and n are even, where each Hi is isomorphic to H, such that V(Hi)={ui,v1,v2,,vn} and E(Hi)={uiv1,uiv2,,uivn}, for all 1im. Define a total labeling f:V(G)E(G){1,2,,p+q} by f(ui)=i and f(vj)=m+j, for all 1im and 1jn.

Case 1: mn.
Now the edges of G can be labeled as shown in Table 1.

The edge label of a n-star-decomposition of G if mn..
f v1 v2 vn1 vn
u1 (m+n) (2m+n) (m+n) (m+n)
+m +1 +((n1)m) +((n1)m+1)
u2 (m+n)+ (2m+n) (m+n) (m+n)
(m1) +2 +((n1)m1) +((n1)m+2)
u3 (m+n)+ (2m+n) (m+n) (m+n)
(m2) +3 ((n1)m2) +((n1)m+3)
uk (m+n)+ (2m+n) (m+n)+((n2)m) (m+n)+(n1)m
(m(k1)) +k +(m(k1)) +k
um1 (m+n)+ (2m+n) (m+n) (m+n)
2 +(m1) +((n2)m+2) +(mn1)
um (m+n)+ (2m+n) (m+n) (m+n)
1 +m +((n2)m+1) +mn


We prove the result for n=k and the result follows for all 1km.
From Table 1 and from definition of f, we get f(Hk)=f(uk)+i=1nf(vi)+i=1nf(ukvi)=k+i=1n(m+i)+i=1nf(ukvi). Now, i=1nf(vi)=(m+1)+(m+2)++(m+n)=mn+(1+2++n)=mn+n(n+1)2. Also i=1nf(ukvi)=((m+n)+(m(k1)))+((m+n)+(m+k))+  +((m+n)+(n2)m+(m(k1)))+((m+n)+(n1)m+k)=((2m+n)(k1))+((2m+n)+k)+((4m+n)(k1))+  ((4m+n)+k)++(((n)m+n)(k1))+(((n)m+n)+k)=2((2m+n)+(4m+n)++(nm+n))+n2(1)=2((2m+2n++nm)+n(n)2)+n2=4m(1+2++n2)+2n2+n2=4m(n(n+2)8)+2n2+n2=mn2+2mn+2n2+n2=n2(m+2)+n(2m+1)2.
Hence i=1nf(ukvi)=n2(m+2)+n(2m+1)2. and is constant for all 1km.
Using the above values, we get f(Hk)=k+mn+n(n+1)2+n2(m+2)+n(2m+1)2=k+2mn+n2+n+n2(m+2)+n(2m+1)2=k+n2(m+3)+2n(2m+1)2. for all 1km. So, {f(H1),f(H2),,f(Hm)=a,a+d,,a+(m1)d} forms an arithmetic progression with a=(1+n2(m+3)+2n(2m+1)2) and common difference d=1. Thus in this case, the graph G is a HV-super-strong-(a,d)-antimagic decomposable.

Case 2: m=n.
Now the edges of G can be labeled as shown in Table 2.

The edge label of a n-star-decomposition of G if m=n.
f v1 v2 vn1 vn
u1 3n 3n+1 (n+1)n (n+1)n+1
u2 3n1 3n+2 (n+1)n1 (n+1)n+2
u3 3n2 3n+3 (n+1)n2 (n+1)n+3
uk 3n(k1) 3n+k (n+1)n(k1) (n+1)n+k
un1 2n+2 4n1 n(n)+2 (n+2)n1
un 2n+1 4n n(n)+1 (n+2)n


We prove the result for n=k and the result follows for all 1kn.
From Table 2 and from definition of f, we get f(Hk)=f(uk)+i=1nf(vi)+i=1nf(ukvi)=k+i=1n(n+i)+i=1nf(ukvi). Now, i=1nf(vi)=(n+1)+(n+2)++(n+n)=(n)n+(1+2++n)=(n)n+n(n+1)2. Also i=1nf(ukvi)=(3n(k1))+(3n+k)+(5n(k1))+(5n+k)+  +((n+1)n(k1))+((n+1)n+k)=(3n+1)+3n+(5n+1)+5n++((n+1)n+1)+(n+1)n=2(3n+5n++(n+1)n)+n2(1)=2n(3+5++(n+1))+n2=2n((1+2+3++(n+1))(2+4+6++n)1)+n2=2n((n+1)(n+2)22(n2)(n+12)21)+n2=2(n2+3n+22(n2+2n)41)+n2=2n(2n2+6n+4n22n44+n2=n(n2+4n+n)2=n3+2n2+2n2+n2=n2(n+2)+(n(2n+1)2. Hence i=1nf(ukvi)=n2(n+2)+n(2n+1)2. and is constant for all 1kn.
Using the above values, we get f(Hk)=k+(n)n+n(n+1)2+n2(n+2)+n(2n+1)2=k+2(n)n+n2+n+n2(n+2)+n(2n+1)2=k+n2(n+3)+2n(2n+1)2. for all 1kn. So, {f(H1),f(H2),,f(Hn)=a,a+d,,a+(n1)d} forms an arithmetic progression with a=(1+n2(n+3)+2n(2n+1)2) and common difference d=1. Thus in this case also, the graph G is a HV-super-strong-(a,d)-antimagic decomposable. ◻

Theorem 2. If a non-trivial H-decomposable graph GKm,n is HV-super-strong-(a,d)-antimagic decomposable graph with both m and n are even and if the sum of edge labels of a decomposition Hj is denoted by f(E(Hj)) then f(E(Hj)) is constant for all 1jm and it is given by f(E(Hj))=n2(m+2)+n(2m+1)2.

Proof. Suppose G is H-decomposable and possesses a HV-super-strong-(a,d)-antimagic labeling f, then by Theorem 1, for each Hj in the H-decomposition of G, we get f(E(Hj))=i=1nf(ujvi)=n2(m+2)+n(2m+1)2 which is true for all 1jm. Thus f(E(Hj)) is constant for all 1km and it is given by f(E(Hj))=n2(m+2)+n(2m+1)2◻

Theorem 3. If a non-trivial H-decomposable graph GKm,n is HV-super-strong-(a,d)-antimagic decomposable graph with both m and n are even and if the sum of vertex labels of a decomposition Hj is denoted by f(V(Hj)) then
{f(V(H1)),f(V(H2)),,f(V(Hm))}={a,a+d,,a+(m1)d} with a=(mn+1)+n(n+1)2 and d=1.

Proof. Suppose G is H-decomposable and possesses a HV-super-strong-(a,d)-antimagic labeling f, then by Theorem 1, for each Hj in the H-decomposition of G, we get f(V(Hj))=f(uj)+i=1nf(vi)=j+i=1n(m+i)=j+((m+1)+(m+2)++(m+n))=j+mn+n(n+1)2. which is true for all 1jm. Thus {f(V(H1)),f(V(H2)),,f(V(Hm))}={a,a+d,,a+(m1)d} with a=(mn+1)+n(n+1)2 and d=1◻

Theorem 4. Let GKm,n be a H-decomposable graph with both m and n are even and if V(G)=U(G)W(G) with |U(G)|=m and |W(G)|=n. let g be a bijection from V(G) onto {1,2,,p} with g(U(G))={1,2,,m} and g(W(G))={(m+1),(m+2),,(m+n=p)} then g can be extended to an HV-super-strong-(a,d)-antimagic labeling if and only if f(E(Hj)) is constant for all 1jm and it is given by f(E(Hj))=n2(m+2)+n(2m+1)2.

Proof. Suppose GKm.n be a H-decomposable graph with both m and n are even and if V(G)=U(G)W(G) with |U(G)|=m and |W(G)|=n. let g be a bijection from V(G) onto {1,2,,p} with g(U(G))={1,2,,m} and g(W(G))={(m+1),(m+2),,(m+n=p)}. Assume that f(E(Hj)) is constant for all 1jm and it is given by f(E(Hj))=n2(m+2)+n(2m+1)2. Define f:V(G)E(G){1,2,,p+q} as f(ui)=g(ui); f(uj)=g(uj) for all 1im; 1jn and the edge labels are in either Table 1 (if mn) or Table 2 (if m=n) then by Theorem 2.1, for each Hj in the H-decomposition of G, we get f(V(Hj))=f(uj)+i=1nf(vi)=j+i=1n(m+i)=j+((m+1)+(m+2)++(m+n))=j+mn+n(n+1)2. which is true for all 1jm. So, we have {f(V(H1)),f(V(H2)),,f(V(Hm))}={a,a+d,,a+(m1)d} with a=(mn+1)+n(n+1)2 and d=1. Hence, f(Hj)=f(V(Hj))+f(E(Hj))=(j+mn+n(n+1)2)+(n2(m+2)+n(2m+1)2)=j+2mn+n2+n+n2(m+2)+n(2m+1)2=j+n2(m+3)+2n(2m+1)2. for every Hj in the H-decomposition of G and for all 1jm. Thus we have, f is an HV-super-strong-(a,d)-antimagic labeling.
Suppose g can be extended to an HV-super-strong-(a,d)-antimagic labeling f of G with with a=1+n2(m+3)+2n(2m+1)2 and d=1. Then by Theorem 2 f(E(Hj)) is constant for all 1jm and it is given by f(E(Hj))=n2(m+2)+n(2m+1)2◻

3. Conclusion

In this paper, we studied the HV-super-strong-(a,d)-antimagic decomposition of Km,n with n1 and both m and n are even.

Conflict of Interest

The author declares no conflict of interests.

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