Justice Ming Chin of the state Supreme Court will speak on Saturday, May 22, at the first of 10 commencements at the University of California, Davis. He replaces the Rev. Jesse Jackson as speaker at the School of Law's ceremony at 10:30 a.m. in Recreation Hall. Stephanie Gadlin, press secretary for the Rainbow/PUSH Coalition, says President Clinton asked Jackson, who is co-chairing the U.S. delegation to the African-African American Summit in Ghana, to remain there through its closing ceremonies Friday night.