+++
title = "Three-valued logic"
author = "Yann Herklotz"
tags = []
categories = []
backlinks = ["4e1"]
forwardlinks = ["4e3", "4e2a"]
zettelid = "4e2"
+++

Three-valued logic, and it's extensions into infinitely-valued logic is
an interesting expansion on propositional logic, where more properties
can be expressed. Especially when one has an evaluation function which
can fail, one will have a result that is either true or false, or
unevaluatable/undefined.

There are many different possible definitions of a three-valued logic,
each with it's positives and it's downsides. It depends on the
application which one should be chosen. Each different logic will have
slightly different definitions of and/or/implication. Three-valued logic
can also have many additional useful connectives, such as weak and
strong and/or.