A federal judge said Tuesday that Eastern Airlines may curtail service but must return to the bargaining table and negotiate over the proposed layoffs of 4,000 employees. U.S. District Judge Barrington D. Parker said Eastern has shown through testimony that it has the right to change schedules, reduce flights and close its hub at Kansas City as the airline has proposed "without first bargaining with the plaintiffs." The plaintiffs are three unions fighting Eastern's plans to fire 4,000 workers.