“…As we saw at the outset, structure functions may record much more than operational state, extending reliability. Examples include expected maximum flow value [12,18,80,94,108,118,162,201], expected cost of a flow [40], expected shortest path length [78,90,139,177], shortest path lengths with recourse [11,172], maximum reliability path length [166], minimum cut value [14], expected weight of a minimum spanning tree [27,99,140], maximum weight of a forest [2], diameter [137], expected number of reachable nodes [175], expected cost of a matching [206], and more general performance metrics [70]. Of particular interest is the expected duration of a PERT project [109,110,143,160,194], i.e., the expected length of a longest path in an acyclic, directed graph.…”