# FunctionsAndOperators

On the SemanticWebBus, not everybody can find a proof, but everybody can check one. In addition to basic stuff like graph matching and modus-ponens, we expect some relations to be ubiquitously understood. These are often called functions and operators.

For exampleFootNote(written in ShorthandRDF), concluding

:jenny :age 15.

from

:jenny :age [is math:sum of (10 5)].

could be spelled out in detail using peano postulates:
the sum of 10 and 5 is the sum of 10 and succ(4),
which is the sum of 11 and 4, and so on. But in practice,
we trust our machines to add
numbersFootNote(with a few noteable exceptions, e.g. overflow, rounding, etc.) consistently, so we'll just
publish lists of numeric functions an operators and all agree on those.

These should be shared between XML and RDF, of course. So let's look at using XQuery 1.0 and XPath 2.0 Functions and Operators in RDF.

- which namespace to use?
`http://www.w3.org/2001/XMLSchema`

or`http://www.w3.org/2001/XMLSchema-datatypes`

? the 2May2003 XML Query draft seems to use the former. Whew! That's what OWL uses too. - NaryRelations

background/context/fodder:

- Functions and Operators by timbl 2003/04/10
- 28Apr semweb cg action
- discussion 14 Mar