P-versus-NP problem[r]: A famous open problem in complexity theory asking whether any decision problem that can be solved by a nondeterministic algorithm in polynomial time can also be solved deterministically in polynomial time. [e]
Spanish missions in California[r]: A series of twenty-one religious outposts and associated support facilities established by Spaniards of the Franciscan Order between 1769 and 1823, in order to spread the Catholic faith among the local Native American populations. [e]