Improved Approximations for Minimim Independent Dominating Set in Bounded Degree Graphs

We consider the problem of finding an independent dominating set of minimum cardinality in bounded degree and regular graphs. We first give an approximate heuristic for MIDS in at most cubic graphs, based on greedy and local search techniques. Then, we consider graphs of bounded degree $B$ and $B$-regular graphs, for $B \ge 4$. In particular, the greedy phase proposed for at most cubic graphs is extended to any $B$ and iteratively repeated until the degree of the remaining graph is greater than 3. Finally, a local search phase is executed on the remaining at most cubic graph. Our algorithms achieve approximation ratios: - 1.923 for cubic graphs; - 2 for at most cubic and 4-regular graphs; - ${{(B^2-2B+2)(B+1)} \over {B^2+1}}$ for B-regular graphs, $B \ge 5$; - ${{(B^2-B+1)(B+1)} \over {B^2+1}}$ for graphs of bounded degree $B \ge 4$.

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