Auto-negotiation uses fastlink pulses to help a device determine the speed, duplex mode and other details of the link partner. However it is not clear from the ieee802.3 autoneg section what happens if 2 devices send fast link pulses at the same time over what will be a future half duplex connection. Is collision possible between them? If yes how are they corrected?
A network connection has dedicated TX and RX pairs, and so the signals do not "collide" during this process.
Collisions occur when the two devices operate in a half-duplex CSMA/CD environment. When one device is transmitting on TX, if it receives any sort of signal on the RX it will register this as a collision, stop transmitting, back off and start the transmission process over again.
The reason for this is that typically a CSMA/CD environment operates with the use of hubs rather than switches/bridges. A hub is a OSI L1 device that simply receives a signal on one port and repeats the signal out all other ports (other then the receiving port). If a hub were to receive a signal on two different ports at the same time, the signal it repeats would be a "combination" of the two signals and unusable.