In my understanding switch can operate in half duplex or in full duplex mode. In half-duplex mode only one wire pair is used, but in full duplex mode two wire pairs are used.
In half duplex mode there can be collisions. But in full duplex mode there wont be any collisions.
I read that each switch port corresponding to a collision domain. But in full duplex there is no collisions. So how can we say "switches break collision domains / each switch port belongs to one collision domain" as there is no collisions in full-duplex mode.