NEW YORK (AP) — The Gap is laying off 1,800 corporate workers, roughly three time the number of headquarters jobs it cut last fall, as the struggling chain cuts costs in a bid to become more nimble. More layoffs at the struggling chain follow similar cuts at large U.S. corporations this year, such as Amazon and McDonald's, with white collar workers taking the brunt of the head count reductions as economy slows. In a regulatory filing Thursday, the San Francisco-based chain, which also owns Banana Republic, Old Navy and Athleta, said employees in its San Francisco and New York offices, as well as upper field positions such as regional store managers, will be impacted.