Complete co-secure domination in graphsSaraswathy, Gisha (Avtor) Menon, Manju K. (Avtor) domination numberco-secure domination numbercomplete co-secure domination numberA dominating set S ⊆ V is a co-secure dominating set if for each u ∈ S there exists v ∈ V \ S such that v is adjacent to u and (S \ {u}) ∪ {v} is a dominating set. The cardinality of a minimum co-secure dominating set in G is called the cosecure domination number of G and is denoted by γcs(G). The study of a co-secure dominating set is important in interconnection networks as it studies its security. In cosecure domination, a guard can ensure the safety of only one of its adjacent unguarded vertices. This motivated us to define a new domination parameter called complete co-secure domination, in which a guard can move to any one of its adjacent unguarded vertices without compromising the protection of G. A co-secure dominating set S is called a complete co-secure dominating set if for every u ∈ S and for every v ∈ V \ S that is adjacent to u, (S \ {u})∪ {v} is a dominating set. The cardinality of a minimum complete co-secure dominating set is called the complete co-secure domination number of G and is denoted by γccs(G). In this paper, we study the complete co-secure domination in graphs and determined the lower and upper bounds and have checked their sharpness. We have proved that for any positive integer m, there exists a graph whose co-secure domination number is m and complete co-secure domination number is b, where m ≤ b ≤ 2m. We characterize graphs G such that γcs(G) = γccs(G). We obtain a condition for which γcs(G) = γccs(G) = γs(G) for graphs with δ(G) ≥ 2, thus partially resolving a question posed in paper from Arumugam, Ebadi and Manrique from 2014. We also obtain the complete co-secure domination number of some families of graphs. Založba Univerze na Primorskem20262026-03-20 11:56:58Članek v reviji22824sl