An encoding is a way of representing a number or expression in terms of another (usually simpler) one. However, multiple expressions can also be encoded as a single expression, as in, for example,
![(a,b)=1/2[(a+b)^2+3a+b]](/images/equations/Encoding/NumberedEquation1.svg) |
which encodes 
and 
uniquely as a single number.
 |  |  |
| 0 | 0 | 0 |
| 0 | 1 | 1 |
| 1 | 0 | 2 |
| 0 | 2 | 3 |
| 1 | 1 | 4 |
| 2 | 0 | 5 |
More generally, any list of positive integers can be uniquely encoded using a Gödel number (Wolfram 2002, p. 1120).
