Ioannis Vaxevanakis | Searcharxiv

arXiv2026

Domination and Coverage Problems under Vulnerability Constraints

In various domination and coverage problems, certain vertices or edges should not be dominated/covered and are designated as vulnerable. Motivated by this, we define the $k$-Vertex Maximum Domination Ratio with Vulnerable Vertices $(k\textit{-}Max \ \mathit{DRVV})$ problem, which extends the budgeted dominating set problem to include vulnerability constraints. We propose an approximation algorithm based on an unbudgeted variant of $k\textit{-}Max \ \mathit{DRVV}$, termed the Maximum Domination Ratio with Vulnerable Vertices $(\mathit{DRVV})$ problem. For bounded-degree graphs of order $n$, our algorithm provides an $O(k/n)$-approximation for the $k\textit{-}Max \ \mathit{DRVV}$ problem. We introduce the Dominating Set with Vulnerable Vertices $(\mathit{DSV})$ problem, reduce it to the Red-Blue Set Cover problem, and derive a $2\sqrt{|V|\cdot(H(Δ_{N})-\frac{1}{2}})$-approximation algorithm, where $|V|$ is the order of the graph, $Δ_N$ is the maximum degree among non-vulnerable vertices and $H$ is the harmonic function. Finally, we examine the Vertex Cover with Vulnerable Edges $(\mathit{VCVE})$ problem, which can be naturally expressed as a special case of the Red-Blue Set Cover problem. We present a polynomial-time $2$-approximation algorithm for the $VCVE$ problem, achieving the best possible ratio.

cs.DS↗

arXiv2026

Approximations for Fault-Tolerant Total and Partial Positive Influence Domination

In $\textit{total domination}$, given a graph $G=(V,E)$, we seek a minimum-size set of nodes $S\subseteq V$, such that every node in $V$ has at least one neighbor in $S$. We define a $\textit{fault-tolerant}$ version of total domination, where we require any node in $V \setminus S$ to have at least $m$ neighbors in $S$. Let $Δ$ denote the maximum degree in $G$. We prove a first $1 + \ln(Δ+ m - 1)$ approximation for fault-tolerant total domination. We also consider fault-tolerant variants of the weighted $\textit{partial positive influence dominating set}$ problem, where we seek a minimum-size set of nodes $S\subseteq V$, such that every node in $V$ is either a member of $S$ or the sum of weights of its incident edges leading to nodes in $S$ is at least half of the sum of weights over all its incident edges. We prove the first logarithmic approximations for the simple, total, and connected variants of this problem. To prove the result for the connected case, we extend the general approximation framework for non-submodular functions from integer-valued to fractional-valued functions, which we believe is of independent interest.

cs.DS↗