1:      1  1 CALL pred app:main/2-0 (det) 
mdb> echo on
Command echo enabled.
mdb> goto 19
      19:      2  2 EXIT pred app:app/3-0 (det) 
mdb> dd_wrong
app([1, 2, 3, 4, 5], [6, 7, 8], [1, 2, 3, 4, 5, 6, 7, 8], int)
Valid? y
Bug not found.
      19:      2  2 EXIT pred app:app/3-0 (det) 
mdb> dd_wrong
app([1, 2, 3, 4, 5], [6, 7, 8], [1, 2, 3, 4, 5, 6, 7, 8], int)
Valid? n
app([2, 3, 4, 5], [6, 7, 8], [2, 3, 4, 5, 6, 7, 8], int)
Valid? n
app([3, 4, 5], [6, 7, 8], [3, 4, 5, 6, 7, 8], int)
Valid? n
app([4, 5], [6, 7, 8], [4, 5, 6, 7, 8], int)
Valid? n
app([5], [6, 7, 8], [5, 6, 7, 8], int)
Valid? n
app([], [6, 7, 8], [6, 7, 8], int)
Valid? n
Incorrect instance found:

app([], [6, 7, 8], [6, 7, 8], int).

      19:      2  2 EXIT pred app:app/3-0 (det) 
mdb> goto 67
append([1, 2, 3, 4, 5], [6, 7, 8], [1, 2, 3, 4, 5, 6, 7, 8]).
      67:      8  2 EXIT pred app:app/3-0 (det) 
mdb> dd_wrong
app([1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5], [6, 7, 8], [1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8], int)
Valid? n
app([2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5], [6, 7, 8], [2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8], int)
Valid? n
app([3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5], [6, 7, 8], [3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8], int)
Valid? n
app([4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5], [6, 7, 8], [4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8], int)
Valid? y
Incorrect instance found:

app([3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5], [6, 7, 8], [3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8], int) :-
	app([4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5], [6, 7, 8], [4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8], int).

      67:      8  2 EXIT pred app:app/3-0 (det) 
mdb> continue -a
append([1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5], [6, 7, 8], [1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8]).
      68:      1  1 EXIT pred app:main/2-0 (det)