The OASIS research group, form INRIA - University of Nice Sophia Antipolis - CNRS is pleased to announce the calculation of N-Queen for N=25.

 
Thanks to the ObjectWeb ProActive library, the computation was achieved in Peer-To-Peer mode (P2P), just using the spare CPU cycles of INRIA desktop machines. As such , the computing platform was highly heterogeneous: GNU/Linux, Windows, various JVMs, PII and PIV from 450 MHz to 3.4 GHz, etc. 

The total duration time was slightly over 6 months, starting October 8th until June 11th, using the spare CPU cycles of about 260 machines. The cumulated computing time was over 50 years!

What is the nQueens Problem?

The nQueens problem consists to place n queens on a nxn chessboard with that no queens are enable to capture each others. More information about this problem are available here.

Computation in the spotlight

Start date: October 8th 2004

End time: June 11th 2005

Computation duration time  = 4444h 54m 52s 854 i.e. 185 days 4 hours 54 minutes 52 seconds 854

Cumulated computation time = 464344h 35m 33s 553 i.e. 53 years 2 days 16 hours 35 minutes 33 seconds 553

This record is registered at: http://www.research.att.com/cgi-bin/access.cgi/as/njas/sequences/eisA.cgi?Anum=000170

Previously n = 24 - September 28 2004

 Solutions for N = 24 :: 227514171973736

Total worker CPU time = 49271h 29m 57s 622 = 2053 days = 5 year and 6 month

Computation duration time = 413h 27m 57s 847 = 17 days