"Insert" is the act of telling the WorkingMemory about the facts. WorkingMemory.insert(yourObject) for example. When you insert a fact, it is examined for matches against the rules etc. This means ALL of the work is done during insertion; however, no rules are executed until you call "fireAllRules()". You don't call "fireAllRules()" until after you have finished inserting your facts. This is a common misunderstanding by people who think the work happens when you call "fireAllRules()". Expert systems typically use the term "assert" or "assertion" to refer to facts made available to the system, however due to the assert become a keyword in most languages we have moved to use the "Insert" keyword; so expect to hear the two used interchangeably.

When an Object is insert it returns a FactHandle. This FactHandle is the token used to represent your insert Object inside the WorkingMemory, it is also how you will interact with the Working Memory when you wish to retract or modify an object.

Cheese stilton = new Cheese("stilton");
FactHandle stiltonHandle = session.insert( stilton );

As mentioned in the Rule Base section a Working Memory may operate in two assertions modes equality and identity - identity is default.

Identity means the Working Memory uses an IdentityHashMap to store all asserted Objects. New instance assertions always result in the return of a new FactHandle, if an instance is asserted twice then it returns the previous fact handle – i.e. it ignores the second insertion for the same fact.

Equality means the Working Memory uses a HashMap to store all asserted Objects. New instance assertions will only return a new FactHandle if a no equal classes have been asserted.