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Energy distribution

Only some particles reach the energy source; particles must share energy so that every action is paid for.

Problem statement and measuresexpand

Each action costs energy, and only \(s\) particles, the sources, can harvest energy from outside. Particles must distribute energy locally so that every particle can act, or so that a given energy-agnostic algorithm runs correctly. Time is in rounds.

Measures: Time, asynchronous rounds.

Unfair adversary

standard settingverified
Time: polynomial gap

Energy can be distributed in \(O(n)\) rounds, against an \(\Omega(n/s)\) lower bound; any conforming energy-agnostic algorithm becomes energy-constrained with \(O(n^2)\) rounds of overhead per action, even under an unfair adversary.

Assumed (added on the last edge are outlined)

+Memoryconstant memory and local communication+Schedulersequential: one particle active at a time

Not assumed

Orientationno common orientation and no chiralityRandomnessdeterministicInitial shapeconnected, holes allowedConnectivity during executionthe system must stay connected
Formal definitions of this setting
Memory: constant memory
Each particle has \(O(1)\) bits of persistent memory and reads or writes neighbours' memory.
Scheduler: sequential
At most one particle is active at any time.
Orientation: no orientation
Each particle labels its six incident directions in its own clockwise or counter-clockwise order, starting anywhere.
Randomness: deterministic
No random choices.
Initial shape: holes allowed
The initial set of occupied nodes induces a connected subgraph; it may enclose empty regions.
Connectivity during execution: stays connected
At every time the occupied nodes induce a connected subgraph.

What is known

Time · asynchronous rounds
polynomial gap
\(O(n)\) against \(\Omega(n/s)\): a factor \(s\).
lower bound
\(\Omega(n/s)\) Daymude et al. 2021
bottleneckdistance
holds when
  • Theorem 9
  • \(s\) energy sources
introductory—
current best
\(O(n)\)

Results, in order of publication

Daymude et al. 2021 current best
Time \(O(n)\)

Introductory and current best (Theorem 8); a self-stabilising spanning forest tolerates crash failures.

Time \(O(n^2\,T_A(n))\)
unfair adversary

Theorem 4: \(T_A(n)\) is the running time of the energy-agnostic algorithm. Composes with the concurrency control framework.

Open questions

None recorded for this variant.

Notes

No orientation is assumed. Checked against the full texts.

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