Computation time for central metabolism metabolic networks of E. coli. Different network configurations yield varying numbers of elementary modes. Left: Candidate narrowing with combinatorial (red filled squares) and algebraic adjacency test (red triangles) shows significant speed up compared to simple approaches. Multithreaded versions (green) provide further speedup of 1/2 to 3/4 with two threads on a Dual-Core processor. Right: Computation time compared with Metatool 5.0 (benchmarks see , Table 1 therein). Both presented algorithm versions are faster for large networks, even if implemented in Java (Metatool: C).