[Slick]

Running away should be determined something like this: the minimum distance between enemies is calculated periodically, say every second. A critical distance is initally established and reduced slightly every second. At any time, if the separation distance is greater than the critical distance, then the combat ends with disengagement.

The numbers should be chosen so as to ensure that combat won't immediately end due to initial placement, and that a faster ship should be able to catch a slower ship without combat ending first.

This way, ships of equal speed will end up disengaging after some time and immobile ships, no matter how close will eventually meet the criteria.

I also agree that disengagement should result in moving the fleeing ship/fleet to another sector. Which sector it moves to should be random so as not to be exploitable in rushing to an enemy homeoworld with a superfast fleet - the slower fleets, being able to set up defensively ahead of time, would (in a "real" battle) block the faster fleet from "retreating forward". Moving the disengaging ship/fleet to another sector is strategically important so as to prevent blockading planets with superfast ships.