Linear-time computation of optimal subgraphs of decomposable graphs. Multiple optima in local search. Efficient algorithms for finding minimum spanning forests of hierarchically defined graphs. David S. Johnson . The many faces of polynomial time.
Fast approximation algorithms for a nonconvex covering problem.
Computational complexities of Diophantine equations with parameters. Better expanders and superconcentrators. Space searching for intersecting objects. Finding critical sets. Ten-Hwang Lai and Alan Sprague .