Iterated Blackboard Sample Clauses

Iterated Blackboard. ‌ The Iterated-Blackboard algorithm uses the reliable broadcast primitives broadcast and accept (Theorem 1) to construct a series of blackboards BB = (BB1, BB2, . . .), the columns of which are indexed by process IDs in [n] and the rows of which are indices in [0, m]. The blackboard proper consists of rows 1, . . . , m; the purpose of row zero is to reduce disagreements between the views of good processes. Every process p maintains BB(p) = (BB(p), BB(p), . . .), where BB(p)(r, i) records the value written by process i to BBt(r, i) and accepted 1 2 t ⊥ by process p, or if no such value has yet been accepted by p. Each process maintains a vector last(p) indicating the position of the last accepted write from each process, i.e., last(p)(i) = (t, r) if p accepted i’s write to BBt(r, i), but has yet to accept any subsequent writes from i to BBt, nor to BBt+1, BBt+2, . . .. Algorithm 5 gives the algorithm Iterated-Blackboard(t) for generating BBt from the perspective of process p. Process p may only begin executing it if t = 1 or if it has finished executing Iterated-Blackboard(t — 1) and therefore already fixed BB(p,t−1) and last(p) . t−1 Algorithm 5 Iterated-Blackboard(t) from the perspective of process p