How to model a counter using an equation?

[svensl]

Does anyone know how to model a counter? Conceptually, the counter counts edge triggered events at its input, accumulates them over some time, before dumping the result to the output.
With model I mean what equation could I use to represent such behaviour?

Thanks,

 

[Lord Loh.]

model

Well I am firing an arrow in the dark...

Edge triggered behaviour can be represented by the differentiation of the input signal.

Pass the derrivative to a threshold fnction that shall return 1 if the derrivative is above a certain level else return 0.

Count the number of 1s you have got.

Honestly tell me svensl... Have I spoken sense?