0 an accident that happens when two vehicles hit each other with force -- （車輛的）碰撞，相撞
1 a strong disagreement -- 衝突，牴觸
In the radio model, the inability to choose direction of transmissions makes the straightforward colouring of the ring insufficient for avoiding collisions.
The total balance of the evolution is: two collisions and seven collapses.
The collisions of other combinations of waves that occur in solving- are simpler.
Note that for cylindrical semi-focusing billiards, the same happens for consecutive collisions with the flat boundary components.
All they do between collisions is to translate rectilinearly while rotating concomitantly.
No longer a result of perspectival extrusions and planar collisions, space is now a product of the hollowing and localized dissolutions of emergent landforms.
All these results assume finite horizon: that is, the free path between collisions must be bounded above.
Delivery rates are more efficient to protoplanetary discs, as the solid grains effectively sputter the incoming material in hypervelocity collisions.
