stigmergy

Name

stigmergy — coordination by the marks left behind, with no one in charge

Synopsis

stigmergy [--no-manager] [--leave-mark N] [--evaporate RATE] --follow
order ← Σ local_acts   (plan = ∅)

Description

stigmergy coordinates independent workers with no supervisor, no schedule, and no direct messages between them. Each worker reads only the marks left in the shared environment at its current position, acts on them, and leaves a mark of its own. The mark left by the last worker is the entire instruction set the next one receives.

There is no plan, and no place a plan could be stored. Coordination is a side effect of accumulation: routes used often are reinforced faster than they decay, routes ignored fade to nothing, and the difference between a good path and a bad one is resolved in the ground rather than in anyone's head. Adding workers costs no coordination overhead, because there is no coordination to bill for.

The environment is both the memory and the message bus. Delete the marks and the colony forgets everything it agreed to, having never agreed to anything.

Options

--no-manager

Run with no supervising process. This is the default and cannot be turned off. There is no code path in which someone is in charge.

--leave-mark N

Deposit N units of trace at the current position. Every worker does this. None of them reads a memo about it first.

--evaporate RATE

Fade old marks at RATE so stale routes stop lying. Required. Set it to zero and the first mistake becomes permanent.

--follow

Move toward the strongest nearby trace, then defer to it. This is the whole strategy.

--shortest

Request the shortest path. Accepted, ignored. The shortest path is not requested; it is the one that outlasts the others.

--meeting

Convene the workers to agree on a plan. Not implemented. Returns immediately. See BUGS.

Exit Status

0

a path emerged. no one takes credit; no one is asked to

0

no path emerged: the marks were laid, the traffic never came. also a success, technically

75

EX_TEMPFAIL: trail evaporated faster than it was reinforced. deploy more ants and try again

78

EX_CONFIG: a supervisor was configured. no supervisor could be located. request logged, then dropped

History

Coined in 1959 by French entomologist Pierre-Paul Grassé, who observed that termites building a mound never coordinate directly but respond to the structure their neighbours have already deposited. He fused Greek stigma, a mark or sign, with ergon, work: the work itself stimulates the next work. In 1992 Marco Dorigo formalised the mechanism as Ant Colony Optimization, letting simulated ants deposit virtual pheromone on graph edges to solve routing, scheduling, and the travelling-salesman problem. The same principle later got a second life describing distributed routing, Wikipedia, and open-source codebases.

Bugs

--meeting returns before doing anything. Filed 1959; the colony was not briefed on the filing, or on anything else.

Setting --evaporate 0 converts the trail into a permanent monument to the first ant's worst decision.

No leader is ever elected. Requests for a leader are written to the ground and answered by whoever walks past.

See Also

controlplane(8), backpressure(3), homoiconicity(3). The living exhibit demonstrates the word in motion:

▸ operate stigmergy

Author

Maintained by the colony, which has held zero meetings, appointed zero supervisors, and has not been briefed. Correspondence is left on the ground and answered by whoever passes next.