1 | initial version |

Although underscores can be used to define new variables

```
sage: var('x,y,z_a')
(x, y, z_a)
sage: z_a
z_a
```

"carrots" cannot be used

```
sage: var('x,y,z^a')
(x, y, z^a)
sage: z^a
Traceback (click to the left of this block for traceback)
...
NameError: name 'z' is not defined
```

This is because in that last statement, `z^a`

, Sage is looking for a variable called `z`

and trying to exponentiate it with some other variable called `a`

. Note that the symbol `^`

is used in Sage for exponentiation. In short, you shouldn't use it to define a new variable.

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