1:      1  1 CALL pred neg_conj.main/2-0 (det) neg_conj.m:14
mdb> echo on
Command echo enabled.
mdb> register --quiet
mdb> break p
 0: + stop  interface pred neg_conj.p/1-0 (semidet)
mdb> continue
       3:      2  2 CALL pred neg_conj.p/1-0 (semidet) neg_conj.m:23 (neg_conj.m:15)
mdb> finish
      22:      2  2 EXIT pred neg_conj.p/1-0 (semidet) neg_conj.m:23 (neg_conj.m:15)
mdb> dd -d 3 -n 7
p(0)
Valid? no
q(0, 0)
Valid? yes
Call r(0)
Unsatisfiable? yes
q(0, 1)
Valid? yes
Call r(1)
Unsatisfiable? yes
Call q(0, _)
Solutions:
	q(0, 0)
	q(0, 1)
Complete? yes
Found incorrect contour:
p(0)
Is this a bug? yes
      22:      2  2 EXIT pred neg_conj.p/1-0 (semidet) neg_conj.m:23 (neg_conj.m:15)
mdb> continue
yes.