Federal Reserve Chairman Alan Greenspan gave Congress a more optimistic appraisal of the U.S. economy Thursday than he did a week ago, saying recent data indicate the first recession in a decade is already over."The recent evidence increasingly suggests that an economic expansion is already well under way, although an array of influences unique to this business cycle seems likely to moderate its speed," Greenspan said in his remarks prepared for delivery to the Senate Committee on Banking, Housing and Urban Affairs.