The production system operates on a forward chaining recognize-act cycle:
Recognize:
All productions are matched against all data
to find the set of all productions that are satisfied by some
subset of the data. (The same production might be
satisfied by multiple sets of data.) The set of satisfied
productions with data bindings is sometimes called the
conflict set.
Act:
The satisfied productions (or, in implementations on a
serial machine, one of them) are fired, which means
their actions are executed. The actions generally make
changes in the working memory. Production systems thus
normally operate in a forward-chaining fashion.