Searching for an OGR in an NP-complete problem. The CPU time required to find an Optimal Golomb Ruler increases rapidly with the length of the ruler. Distributed.net is now working on an OGR-25 (25 mark optimal Golomb ruler) challenge. The OGR-24 project was restarted on July 13, 2000 and OGR-25 started on August 1, 2000. Neither OGR-24 or OGR-25 is solved yet.