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تسجيل مستخدم جديدMimicking Networks Parameterized by Connectivity
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Given a graph $G=(V,E)$, capacities $w(e)$ on edges, and a subset of terminals $mathcal{T} subseteq V: |mathcal{T}| = k$, a mimicking network for $(G,mathcal{T})$ is a graph $(H,w)$ that contains copies of $mathcal{T}$ and preserves the value of minimum cuts separating any subset $A, B subseteq mathcal{T}$ of terminals. Mimicking networks of size $2^{2^k}$ are known to exist and can be constructed algorithmically, while the best known lower bound is $2^{Omega(k)}$; therefore, an exponential size is required if one aims at preserving cuts exactly. In this paper, we study mimicking networks that preserve connectivity of the graph exactly up to the value of $c$, where $c$ is a parameter. This notion of mimicking network is sufficient for some applications, as we will elaborate. We first show that a mimicking of size $3^c cdot k$ exists, that is, we can preserve cuts with small capacity using a network of size linear in $k$. Next, we show an algorithm that finds such a mimicking network in time $2^{O(c^2)} operatorname{poly}(m)$.
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