| The universal Turing machine is a hypothetical device that scans a digital tape and, in principle, can solve any computable problem. |
| In particular, composite fields are naturally computable using the intersection of regions in the separate fields. |
| Turing also showed that there are universal Turing machines — machines that can compute any function computable by any other Turing machine. |
| Atom depth is an easily computable quantity, yet it allows one to detect some general features of proteins and protein domains. |
| Analyze impacts of prospective trade agreements, using computable general equilibrium models as well as other economic techniques. |
| A more refined question is to ask what is computable in polynomial time, or P time. |
