Making Belnap's "Useful 4-Valued Logic" Useful
Abstract
In 1977 Nuel Belnap published two articles, "How a Computer Should Think"
and "A Useful Four-Valued Logic", in which he defined a four-valued logic
called FDE (First Degree Entailment).
However, FDE does not allow entailments within statements, and no conditional
connective is defined.
As such, it is not really computationally "useful".
This work proposes conditional connectives to add to FDE, and describes the
implementation of a reasoning tool for FDE with a conditional connective,
with experimental results.
With the addition of a conditional connective FDE starts to become truly
computationally useful.