"Communicating Sequential Processes" by C.A.R. Hoare is probably the classic text on the subject. It is  available as a free download from http://www.usingcsp.com/.

--- Rod

Experiment with a few ideas then do whatever makes sense in the game. Just make sure that the rules are applied consistently.

For example, if the platform can crush you, then it should also be able to crush your adversaries. Gameplay could then include the ability to lure adversaries to their doom on top of a rising platform / beneath a falling platform.

Another option is to have the platform reverse direction when its occupant would otherwise be crushed.

--- Rod