The disjunction of a set of subformulas is true if any of the subformulas are true.
The symbol we use for disjunction is `∨`

.
The disjunction of zero subformulas is trivially false.
The disjunction of a single subformula is equivalent to that subformula.

```
``` A

```
``` A ∨ ~A

```
``` A ∨ B ∨ C

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

stands for true, and `f`

stands for false.

` A ` | ` B ` | ` A ∨ B ` |
---|---|---|

`f` | `f` | `f` |

`f` | `t` | `t` |

`t` | `f` | `t` |

`t` | `t` | `t` |

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

Copyright © 2014 Barry Watson. All rights reserved.