focal object: Any named item that is an instance of a class named in a generic rule or any subclass of the class. You explicitly invoke generic rules by their focal object to limit the scope of processing. See also focal class.
formula: An equation that provides simulated values for a variable. The evaluation of a formula starts a new process. See also generic formula and specific formula.
forward chaining: A technique of invoking "if" rules by using data-driven processing whereby G2 invokes any rule whose antecedent refers to an attribute, parameter, or variable whose value has changed. Forward chaining creates a new process for each instance of variable that receives a new value. Contrast with backward chaining.