Fig. 4From: Tree diet: reducing the treewidth to unlock FPT algorithms in RNA bioinformaticsA graph G (left) with treewidth 3. Deleting edge cd gives treewidth 2, implying that \(G\in \mathsf{Treewidth 2+1e}\). However, if one contracts edge cd, then the resulting graph (right) has treewidth 3, and deleting any single edge does not decrease the treewidth. This example shows that the graph family Treewidth 2+1e is not minor-closedBack to article page