• Kernel(s) for Problems with No Kernel: On Out-Trees with Many Leaves 

      Fernau, Henning; Fomin, Fedor; Lokshtanov, Daniel; Raible, Daniel; Saurabh, Saket; Villanger, Yngve (Peer reviewed; Journal article, 2009)
      The {\sc \(k\)-Leaf Out-Branching} problem is to find an out-branching, that is a rooted oriented spanning tree, with at least \(k\) leaves in a given digraph. The problem has recently received much attention from the ...
    • Minimum Fill-in of Sparse Graphs: Kernelization and Approximation 

      Fomin, Fedor; Geevarghese, Philip; Villanger, Yngve (Peer reviewed; Journal article, 2011)
      The Minimum Fill-in problem is to decide if a graph can be triangulated by adding at most k edges. The problem has important applications in numerical algebra, in particular in sparse matrix computations. We develop ...
    • Parameterized complexity of Eulerian deletion problems 

      Cygan, Marek; Pilipczuk, Marcin; Marx, Dániel; Pilipczuk, Michal Pawel; Schlotter, Ildikó (Peer reviewed; Journal article, 2014-01)
      We study a family of problems where the goal is to make a graph Eulerian, i.e., connected and with all the vertices having even degrees, by a minimum number of deletions. We completely classify the parameterized complexity ...
    • Solving the 2-disjoint connected subgraphs problem faster than 2ⁿ 

      Cygan, Marek; Pilipczuk, Marcin; Pilipczuk, Michal Pawel; Wojtaszczyk, Jakub Onufry (Peer reviewed; Journal article, 2014-10)
      The 2-DISJOINT CONNECTED SUBGRAPHS problem, given a graph along with two disjoint sets of terminals Z1,Z2, asks whether it is possible to find disjoint sets A1,A2, such that Z1 ⊆ A1, Z2 ⊆ A2 and A1,A2 induce connected ...