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Near-gathering

Robots must get within a small distance of each other without ever colliding.

Problem statement and measuresexpand

Robots with limited visibility, each seeing only the robots within its visibility radius \(V\), start at distinct points whose visibility graph (two robots joined by an edge when they are within distance \(V\)) is connected. They must reach a configuration in which every robot sees all others, without a collision (two robots at the same point) ever happening.

Measures: Time, rounds (FSYNC, SSYNC) or epochs (ASYNC) until the task is done; "finite" when only solvability is known; Colours, colours of the light per robot (0 for oblivious robots).

tight near-optimal polynomial gap unknown impossible· rows follow the assumption tree; each cell: best upper bound vs lower bound, and what forces the lower bound
Setting
Time
Colours
Scheduler + point, + transparent, + no faults
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—
ASYNC, limited visibility, one common axis ASYNC, + one axis
1 open · 1 results
unknown \(\text{finite}\) vs —
tight \(0\) vs —
SSYNC, limited visibility, disoriented + SSYNC
1 open · 1 results
tight \(O(\Delta_0^2)\) vs \(\Omega(\Delta_0^2)\) locality
tight \(0\) vs —

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