Writing an abductive theory file

First, we need to encode the problem in an abductive theory source file, suppose. An abductive theory has three parts: the background knowledge, the abducible predicates and the integrity constraints.

The background knowledge is a set of Prolog clauses (either rules or facts), e.g.,

car_doesnt_start(X) :- battery_flat(X).
car_doesnt_start(X) :- has_no_fuel(X).

lights_go_on(mycar).
fuel_indicator_empty(mycar).

The integrity constraints are Prolog rules with the head being ic, e.g.,

ic :- battery_flat(X), lights_go_on(X).
ic :- has_no_fuel(X), \+ fuel_indicator_empty(X), \+ broken_indicator(X).

Note that negation is written as the same as the Prolog negation, i.e., atom preceded by the Prolog's not operator - ${\tt\backslash+}$.

An abductive predicate is declared using abducible/1, e.g.,

abducible(battery_flat(_)).
abducible(has_no_fuel(_)).
abducible(broken_indicator(_)).