What is a Path Convergence & Divergence?
Path convergence is multiple network paths merging into one activity — that node needs all of them finished, so its risk multiplies with each incoming path. Divergence is one activity fanning out into several successors — a slip there propagates everywhere downstream.
Convergence points are where schedules quietly die: five predecessor paths each 90% likely to be on time gives the merge node roughly a 59% chance. Schedule reviews should hunt merges the way risk reviews hunt single points of failure.
Formula
P(merge on time) ≈ product of each converging path's on-time probability
Worked example
"Start commissioning" waits on mechanical completion, electrical completion, controls software, and permit sign-off — four paths converging. Each is individually healthy; the planner still flags the node, adds a two-week buffer in front of it, and sequences pre-commissioning checks that need only two of the four. When the software path slips (of course it's the software), commissioning starts on the partial front anyway. Convergence respected, date preserved.