1. Apparatus for forming a fast optimal or near optimal association based on satisfying global constraints expressed in an association matrix, comprising: means including a state memory for storing signals representative of neuron values x.sub.i by addresses corresponding to row and column indexes of the association matrix; means including an active list memory for storing signals representative of a list of all active neurons that contribute to the formation of a change .DELTA.x.sub.i in the neuron value signals stored in the state memory; means for processing the signals representative of active neurons to approximate trajectories representing an evolution of neuron states at discrete intervals of time .DELTA.t to obtain signals representative of the change .DELTA.x.sub.i in the neurons at said intervals; means for replacing the neuron value signals stored in the state memory by signals representative of x.sub.i +.DELTA.x.sub.i ; means for writing the row and column address of x.sub.i into the active list memory for a next iteration, if any .DELTA.x.sub.i is less than zero; means for replacing all neuron value signals corresponding to active neurons stored in the active list by a signal representative of 1.0 if, after any iteration, .DELTA.X.sub.i is zero or greater.