The problem with demonstrating this equivalence is that signalling must be expensive to work; there's no 'low-cost' substitute for signalling. One example is na

The problem with demonstrating this equivalence is that signalling must be expensive to work; there's no 'low-cost' substitute for signalling. One example is natural diamond engagement rings; they must be expensive to signal commitment; an imitation doesn't do the job, no matter how beautiful.