Cooperation

Overview

In tile assembly models, cooperation is the process by which two or more glues on nearby tiles contribute enough strength to allow a tile to attach when one of the glues would not have been sufficient. Most interesting tile systems in the aTAM (such as Turing machine simulations, binary counters, and efficient shape builders) seem to require cooperation, which has lead to the long standing conjecture that non-cooperative tile assembly systems cannot perform arbitrary computation.

Weak-Cooperation

Cooperation normally requires a binding threshold parameter (temperature) of 2 or more; however, in a variety of tile assembly models, this sort of behavior can be simulated through mechanisms other than glue binding, such as geometric hindrance or negative glues. Models in which this occurs are called *weakly-cooperative* and are often capable of universal computation even at temperature 1.