test :- a(_), fail.
test :-
	( a(_) -> writeln('1. a(X) is true') ; writeln('1. a(X) is false') ),
	( b(_) -> writeln('1. b(X) is true') ; writeln('1. b(X) is false') ),
	( c(_) -> writeln('1. c(X) is true') ; writeln('1. c(X) is false') ),
	( d(_) -> writeln('1. d(X) is true') ; writeln('1. d(X) is false') ),
	( e(_) -> writeln('1. e(X) is true') ; writeln('1. e(X) is false') ),
	( f(_) -> writeln('1. f(X) is true') ; writeln('1. f(X) is false') ),
	( g(_) -> writeln('1. g(X) is true') ; writeln('1. g(X) is false') ),
	fail.
test :- a(1), fail.
test :-
	( a(1) -> writeln('2. a(1) is true') ; writeln('2. a(1) is false') ),
	( b(1) -> writeln('2. b(1) is true') ; writeln('2. b(1) is false') ),
	( c(1) -> writeln('2. c(1) is true') ; writeln('2. c(1) is false') ),
	( d(1) -> writeln('2. d(1) is true') ; writeln('2. d(1) is false') ),
	( e(1) -> writeln('2. e(1) is true') ; writeln('2. e(1) is false') ),
	( f(1) -> writeln('2. f(1) is true') ; writeln('2. f(1) is false') ),
	( g(1) -> writeln('2. g(1) is true') ; writeln('2. g(1) is false') ).

%--------------------------------------------------------------

%
% The non-propositional version of lmod10.P
%

:- table a/1, b/1, c/1, d/1, e/1, f/1, g/1.

a(X) :- b(X), d(X).

b(X) :- c(X).
b(_).
b(X) :- sk_not(e(X)).

c(X) :- b(X), fail.

d(X) :- e(X), f(X), sk_not(g(X)).

e(_).

f(X) :- sk_not(c(X)), e(X).
f(X) :- sk_not(e(X)).
f(X) :- g(X).

g(X) :- f(X).