In
mathematics
Mathematics is a field of study that discovers and organizes methods, Mathematical theory, theories and theorems that are developed and Mathematical proof, proved for the needs of empirical sciences and mathematics itself. There are many ar ...
, Kleene equality,
or strong equality, (
) is an equality operator on
partial functions, that states that on a given argument either both functions are undefined, or both are defined and their values on that arguments are equal.
For example, if we have partial functions
and
,
means that for every
:
*
and
are both defined and
* or
and
are both undefined.
Some authors
[
] are using "quasi-equality", which is defined like this:
where the down arrow means that the term on the left side of it is defined.
Then it becomes possible to define the strong equality in the following way:
References
*
Computability theory
Equivalence (mathematics)
{{mathematics-stub