Abstract
The 2-Disjoint Connected Subgraphs problem asks if a given graph has two vertex-disjoint connected subgraphs containing pre-specified sets of vertices. We show that this problem is NP-complete even if one of the sets has cardinality 2. The Longest Path Contractibility problem asks for the largest integer ℓ for which an input graph can be contracted to the path P ℓ on ℓ vertices. We show that the computational complexity of the Longest Path Contractibility problem restricted to P ℓ-free graphs jumps from being polynomially solvable to being NP-hard at ℓ= 6, while this jump occurs at ℓ= 5 for the 2-Disjoint Connected Subgraphs problem. We also present an exact algorithm that solves the 2-Disjoint Connected Subgraphs problem faster than O∗(2n) for any n-vertex P ℓ-free graph. For ℓ= 6, its running time is O∗(1.5790n) . We modify this algorithm to solve the Longest Path Contractibility problem for P 6-free graphs in O∗(1.5790n) time.
| Original language | English |
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| Title of host publication | Computer Science - Theory and Applications, Fourth International Computer Science Symposium in Russia, CSR 2009, Novosibirsk, Russia, August 18-23, 2009. Proceedings |
| Editors | Anna E. Frid, Andrey Morozov, Andrey Rybalchenko, Klaus W. Wagner |
| Publisher | Springer |
| Pages | 143-154 |
| Number of pages | 12 |
| ISBN (Electronic) | 978-3-642-03351-3 |
| ISBN (Print) | 978-3-642-03350-6 |
| DOIs | |
| Publication status | Published - 2009 |
| Externally published | Yes |
| Event | 4th International Computer Science Symposium in Russia, CSR 2009 - Novosibirsk, Russian Federation Duration: 18 Aug 2009 → 23 Aug 2009 Conference number: 4 |
Publication series
| Name | Lecture Notes in Computer Science |
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| Publisher | Springer |
| Volume | 5675 |
Conference
| Conference | 4th International Computer Science Symposium in Russia, CSR 2009 |
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| Abbreviated title | CSR 2009 |
| Country/Territory | Russian Federation |
| City | Novosibirsk |
| Period | 18/08/09 → 23/08/09 |