关键词：顺序编程；并行机编程；递归单程序
摘 要：We design RSPMD extensions for the Titanium language, including a hierarchical team data structure and lexically-scoped constructs for operating over teams. We demonstrate that these extensions prevent erroneous use of teams that would result in deadlock. In addition, we present a runtime mechanism for ensuring proper use of both global collective operations and collectives over teams, eliminating more potential sources of deadlock.