Teodor Gabriel Crainic Gloria Cerasela Crisan Michel Gendreau Nadia Lahrichi Walter Rei Multi-thread integrative cooperative optimization for rich combinatorial problems. 1-8 2009 IPDPS http://dx.doi.org/10.1109/IPDPS.2009.5161124 conf/ipps/2009 db/conf/ipps/ipdps2009.html#CrainicCGLR09