1:      1  1 CALL pred gcf:main/2-0 (cc_multi) 
mdb> echo on
Command echo enabled.
mdb> goto 22
      22:      2  2 EXIT pred gcf:a/1-0 (nondet) 
mdb> dd_wrong
a(11)
Valid? y
Bug not found.
      22:      2  2 EXIT pred gcf:a/1-0 (nondet) 
mdb> dd_wrong
a(11)
Valid? n
f(11)
Valid? n
Incorrect instance found:

f(11).

      22:      2  2 EXIT pred gcf:a/1-0 (nondet) 
mdb> goto 29
      29:      2  2 EXIT pred gcf:a/1-0 (nondet) 
mdb> dd_wrong
a(12)
Valid? n
f(12)
Valid? y
c(2, 12)
Valid? y
g(2)
Valid? n
Incorrect instance found:

g(2).

      29:      2  2 EXIT pred gcf:a/1-0 (nondet) 
mdb> goto 41
      41:      2  2 EXIT pred gcf:a/1-0 (nondet) 
mdb> dd_wrong
a(20)
Valid? n
f(20)
Valid? y
c(3, 20)
Valid? y
g(3)
Valid? y
Incorrect instance found:

a(20) :-
	g(3),
	c(3, 20),
	f(20).

      41:      2  2 EXIT pred gcf:a/1-0 (nondet) 
mdb> c
yes(20)