Dyna Glossary

functor

The constructor of a term, such as path in path(1,2).

null

The value of items that have no rules contributing aggregands. Null annihilates expressions (e.g. \(\mbox{null} + 2\) is \(\mbox{null}\)) and is the unit of aggregations (e.g. \(\sum\{\mbox{null}, 1, \mbox{null}, 2\}\) is just \(\sum\{1,2\}\)).