Single-valuedness is a property of an expression occurring in a SPMD program and states that concomitant evaluations of this expression lead to the same value at all processes. Although widely used, this property still lacks a formal definition, which is necessary to tackle the subtleties of the notion of concomitance. First, we propose such a definition in which the states of all processes can be compared when they reach textually aligned program points. These program points, of which all processes execute exactly the same textual instances, act as logical global synchronization barriers. Single-valuedness is then defined at these program points. Secondly, we show how textual alignment and single-valuedness can be used to ensure proper use of Direct Remote Memory Access (DRMA) in BSP programs.

单值性是SPMD程序中出现的表达式的一个属性，并指出对该表达式的伴随求值在所有过程中都导致相同的值。尽管广泛使用，但此属性仍缺乏正式定义，这对于解决conception概念的微妙之处是必需的。首先，我们提出这样一个定义，其中所有进程的状态达到文本对齐的程序点时都可以进行比较。这些程序点（其中所有进程都执行完全相同的文本实例）充当逻辑全局同步屏障。。然后在这些程序点定义单值。其次，我们展示了如何使用文本对齐方式和单值方式来确保BSP程序中正确使用直接远程内存访问（DRMA）。