It's quite common to have a situation where in the short term y is a function of x, and in the longer term equilibrium-x is a function of ambient-y. The cylind

It's quite common to have a situation where in the short term y is a function of x, and in the longer term equilibrium-x is a function of ambient-y. The cylinder-with-a-piston used to teach Boyle's law in secondary-school physics is a familiar example: in the short term pressure is a function of volume; in the longer term volume is a function of (external) pressure.