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9. Flex Predicates 130<br />
Examples<br />
<strong>flex</strong> toolkit<br />
forward_chain( fcfs,<br />
true,<br />
prescription_made,<br />
fixed,<br />
prescription_rule_group ) .<br />
forward_chain( crss,<br />
misfire,<br />
fail,<br />
once,<br />
all ) .<br />
forward_chain( +Selection,+Misfire,+Termination,+Update,+Agenda,-Sequence )<br />
forward_chain/6 behaves exactly as forward_chain/5, except that<br />
an additional piece of information is returned: Sequence is the list of rule<br />
names which were actually fired during the forward chaining session.<br />
forward_chain(+Selection,+Misfire,+Termn,+Update,+Agenda,-Sequence,-Result)<br />
forward_chain/7 behaves exactly as forward_chain/6, except that<br />
an additional piece of information, the Result, is returned.<br />
There are two situations in which the forward chaining can terminate, and<br />
the Result parameter reflects this.<br />
0 The Termination criterion was eventually satisfied.<br />
1 A situation was reached in which no rules could be selected.<br />
front( +Name,+Names,-Newnames )<br />
This is a built-in program for re-organising the rule agenda after each cycle<br />
of the forward chaining engine. It brings the most recently fired rule to the<br />
front of the agenda, and is defined by the program:<br />
front( Name, Names, [Name|Newnames]) :-<br />
once( Name, Names, Newnames ).<br />
inclusion( +List,+Term )<br />
The Term and all of the members of the List are first of all dereferenced.<br />
If Term is itself a list, then a check is made that all of its members are also<br />
members of the dereferenced List. Otherwise, the dereferenced Term is a<br />
member of the dereferenced List.<br />
Examples<br />
?- inclusion( [a,b,c,d,e], [c,e,c] ).
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