STOCKHOLM, Sweden - Israeli and U.S. citizen Robert Aumann and American Thomas Schelling won the 2005 Nobel Memorial Prize in Economic Sciences today for their work on game theories that help explain economic conflicts, including trade and price wars.

"Why do some groups of individuals, organizations and countries succeed in promoting cooperation while others suffer from conflict?" the Royal Swedish Academy of Sciences said in announcing the award.

Schelling, 75, is a professor at the University of Maryland's department of economics and a professor emeritus at Harvard. Aumann, 84, is a professor at the Center for Rationality at the Hebrew University of Jerusalem.

It was the sixth straight year that Americans have won the prize, or had a share in it.

Aumann and Schelling were cited for using game-theory analysis to "explain economic conflicts such as price wars and trade wars, as well as why some communities are more successful than others in managing common-pool resources.

BAGHDAD, Iraq - Insurgents launched a new salvo of attacks five days ahead of the country's crucial constitutional referendum, killing at least 12 Iraqis with suicide car bombs, roadside bombs and drive-by shootings today, police said.Five mortar shells also were fired at a hotel in the southern city of Hillah where a U.S. embassy regional office is based. One round hit the building and left a large hole in a wall but no casualties were reported, police said.The latest attacks came as Shiite and Kurdish officials negotiated last-minute changes to the constitution with Sunni Arab leaders in hopes of winning their support ahead of Saturday's referendum. U.S. officials were mediating.Sunni-led insurgent groups have demanded a boycott in the vote and were staging attacks across the country, killing hundreds of Iraqis the last two weeks.On Sunday, militants killed 13 Iraqis, including a Shiite teacher who was dragged out of his classroom and shot to death at a college in the town of Samarra, north of Baghdad.With today's death toll, at least 331 people have been killed across Iraq in the last 15 days. They include nine American soldiers.

BERLIN - Conservative leader Angela Merkel was set to become Germany's first female chancellor under a power-sharing agreement that would end Gerhard Schroeder's seven years in office, party officials said today.The deal was contingent on votes by party conferences and in parliament, a process that could take several weeks. It's already been approved by party leadership committees.Schroeder's Social Democrats extracted a high price for the chancellor's backing down from his demands to continue in office: his party would get eight seats in the Cabinet, compared with six for Merkel's group, said the officials, who spoke on condition of anonymity because they weren't authorized to speak publicly.Merkel forced Schroeder to drop his demand to be chancellor, saying that as head of the party with the largest number of seats, the job belonged to her. She would be the first woman to lead Germany and the first person from the formerly communist east to hold the job.