المستخلص: |
For a graph G = (V, E), a function f: V → {0,1,2} is a perfect Roman dominating function (PRDF) on G if every υ ∈ V with f (υ) = 0 is adjacent to exactly one vertex u with f (u) = 2. The sum Συ∈v (υ) is the weight w (f) of k. The perfect Roman domination number (G) of G is least positive integer k such that there is a PRDF f on G with w (f) ≤ k. A function f: v → {0,1,2} is a perfect Italian dominating function (PIDF) on G if for every υ ∈ V with f (υ) = 0, Σu∈N (u) = 2. The sum Συ∈v (υ) is the weight w (f). The perfect Italian domination number (G) of G is least positive integer K such that there is a PIDF f on G with w (f) ≤ k. Perfect Roman domination and perfect Italian domination are variants of Roman domination, which was originally introduced as a defensive strategy of the Roman Empire. In this article, we prove that the perfect Roman domination and perfect Italian domination problems for Cartesian product graphs are NP-complete. We also give an upper bound for (G), where G is the Cartesian product of paths and cycles.
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