+++
title = "Kleene and Priest logics"
author = "Yann Herklotz"
tags = []
categories = []
backlinks = ["4e2b", "4e2"]
forwardlinks = ["4e2b", "4e2a1"]
zettelid = "4e2a"
+++

These logics are the more "standard", and seem to be the most
straightforward definition of three-valued logic. For example, it has a
lazy or and lazy and, becoming true and false when the answer could be
nothing else. Otherwise, the result can also be undefined.

| AND | F   | U   | T   |
|-----|-----|-----|-----|
| F   | F   | F   | F   |
| U   | F   | U   | U   |
| T   | F   | U   | T   |

| OR  | F   | U   | T   |
|-----|-----|-----|-----|
| F   | F   | U   | T   |
| U   | U   | U   | T   |
| T   | T   | T   | T   |

Then, implication can be defined in terms of AND and OR. In addition to
that NEG(U) = U.

| A-\>B | F   | U   | T   |
|-------|-----|-----|-----|
| F     | T   | T   | T   |
| U     | U   | U   | T   |
| T     | F   | U   | T   |