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Fixed-Parameter Complexity of Minimum Profile Problems. AbstractAn ordering of a graph $G=(V,E)$ is a one-to-one mapping $\alpha:\ V\dom \{1,2,\ldots, |V|\}.$ The profile of an ordering $\alpha$ of $G$ is $\prf_{\alpha}(G)=\sum_{v\in V}(\alpha(v)-\min\{\alpha(u):\ u\in N[v]\})$; here $N[v]$ denotes the closed neighborhood of~$v$. The profile $\prf(G)$ of $G$ is the minimum of $\prf_{\alpha}(G)$ over all orderings $\alpha$ of $G$. It is well-known that $\prf(G)$ equals the minimum number of edges in an interval graph $H$ that contains $G$ as a subgraph. We show by reduction to a problem kernel of linear size that deciding whether the profile of a connected graph $G=(V,E)$ is at most $|V|-1+k$ is fixed-parameter tractable with respect to the parameter $k$. Since $|V|-1$ is a tight lower bound for the profile of a connected graph $G=(V,E)$, the parameterization above the guaranteed value $|V|-1$ is of particular interest.
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