The students at an encampment at Columbia University who inspired a wave of pro-Palestinian demonstrations across the country dug in for their 10th day Friday, as administrators and police at college campuses from California to Connecticut wrestle with how to address protests that have seen scuffles with police and hundreds of arrests. Officials at Columbia and some other schools have been negotiating with student protesters who have rebuffed police and doubled down. Other schools have quickly turned to law enforcement to douse demonstrations before they can take hold. After a tent encampment popped up Thursday at Indiana University Bloomington, police...