We start by defining the prediction rule. Figure 4.1 specifies the procedure.
Figure 4.1: The procedure for prediction.
Prediction will be performed
on active items AL and will return true or false depending
on whether a new item has been added to the agenda
(see line (1)). It will predict instantiations 
[Rule] of all rules
Rule in the grammar G whose head HEAD(Rule) unifies
with the restriction of the selected element of the active item, denoted as
(SEL(AL))
(line (3)) and inserts new items (line (4)) into the agenda Agenda
according to a given priority determined by the function PRIO
individually for each new item (line (5)).
Figure 4.2: The procedure for passive-completion.