Answer
In archeology, seriation is the name of a method for ordering sparsely populated matrices according to the unimodal model. It is used for the relative dating of artefacts from different sites in order to put them in a chronological order.
A unimodal model exists when a phenomenon initially becomes more frequent, but after a maximum becomes rarer again. This is the assumption made by archaeologists for phenomena along the time axis: something does not yet exist; it is invented and then occasionally appears; it is becoming increasingly popular and popping up frequently; it is replaced by something new, out of fashion again and less often in the spectrum of finds until it disappears. Seriation is the adequate mathematical procedure for arranging tables that are subject to such phenomena in a suitable manner, so that they ultimately show the closed finds and the types in a chronological order.
