RVO (Reciprocal Velocity Obstacles)
Local collision avoidance where each agent takes half the responsibility for dodging, so two who meet don't wobble.
A velocity obstacle (Fiorini & Shiller, 1998) is the set of velocities that eventually steer you into another object. Trouble starts when both agents dodge at once: each assumes the other will hold course, both change direction, and next frame the mistake repeats the other way — an oscillation that looks like two people shuffling in a doorway.
Jur van den Berg, Ming Lin and Dinesh Manocha fixed it in 2008 with reciprocity: each agent takes only half the avoidance manoeuvre and trusts its neighbour to take the rest. The result is smooth, stable paths through dense crowds. ORCA superseded it three years later.