The negation of a subformula is true if the subformula is false,
and the negation of a subformula is false if the subformula is true.
The symbol we use for negation is `¬`

.

The truth table below shows all possible combinations for a negation.
Here `t`

stands for true, and `f`

stands for false.

` A ` | ` ¬A ` |
---|---|

`f` | `t` |

`t` | `f` |

Doets, Kees. *From Logic to Logic Programming.* MIT Press, 1994.

Copyright © 2014 Barry Watson. All rights reserved.