Phase Transition in the Number Partitioning Problem
  Number partitioning is an NP-complete problem of combinatorial optimization. A statistical mechanics analysis reveals the existence of a phase transition that separates the easy from the hard to solve instances and that reflects the pseudo-polynomiality of number partitioning. The phase diagram and the value of the typical ground state energy are calculated. 
Stephan Mertens (Otto-von-Guericke Universitat, Magdeburg)