Index Out of Range Error

[damianoazzolini]

Hi, I'm testing a simple program, but, as the title says, I get an index out of range error.
These are my files, stored in a folder called test:

bk.pl

bird(alice).
bird(betty).
can(alice,fly).
can(betty,swim).
ability(fly).
ability(swim).

not_can(X):- \+can(X).

exs.pl

pos(penguin(betty)).
neg(penguin(alice)).

bias.pl

head_pred(penguin,1).

body_pred(bird(bird), 1).
body_pred(can(bird,ability), 4).

type(penguin,(bird)).
type(bird,(bird)).
type(can(bird,ability)).

Here the command I run

> python3 p3 popper.py examples/test/ --debug
15:35:27 Max rules: 1
15:35:27 Max vars: 6
15:35:27 Max body: 6
15:35:27 Num. pos examples: 1
15:35:27 Num. neg examples: 1
Traceback (most recent call last):
  File "popper.py", line 8, in <module>
    prog, score, stats = learn_solution(settings)
  File "/mnt/c/Users/damia/Desktop/Ricerca/Repos/Popper/popper/loop.py", line 206, in learn_solution
    timeout(settings, popper, (settings,), timeout_duration=int(settings.timeout),)
  File "/mnt/c/Users/damia/Desktop/Ricerca/Repos/Popper/popper/util.py", line 63, in timeout
    result = func(*args, **kwargs)
  File "/mnt/c/Users/damia/Desktop/Ricerca/Repos/Popper/popper/loop.py", line 59, in popper
    generator = Generator(settings, grounder)
  File "/mnt/c/Users/damia/Desktop/Ricerca/Repos/Popper/popper/generate.py", line 48, in __init__
    solver.ground([('base', [])])
  File "/home/damiano/anaconda3/envs/deepstochlog/lib/python3.7/site-packages/clingo/control.py", line 339, in ground
    self._rep, c_parts, len(parts), c_cb, c_data), data)
  File "/home/damiano/anaconda3/envs/deepstochlog/lib/python3.7/site-packages/clingo/_internal.py", line 65, in _handle_error
    raise RuntimeError(msg)
RuntimeError: Traceback (most recent call last):
  File "/home/damiano/anaconda3/envs/deepstochlog/lib/python3.7/site-packages/clingo/script.py", line 202, in _pyclingo_call
    _ffi.new_handle(_PYTHON_SCRIPT))
  File "/home/damiano/anaconda3/envs/deepstochlog/lib/python3.7/site-packages/clingo/script.py", line 165, in _pyclingo_script_call
    ret = script.call(_py_location(location), py_name, py_args)
  File "/home/damiano/anaconda3/envs/deepstochlog/lib/python3.7/site-packages/clingo/script.py", line 139, in call
    return fun(*arguments)
  File "<string>", line 3, in pytype
IndexError: list index out of range

[andrewcropper]

The bias file is incorrect. It should be:

head_pred(penguin,1).
body_pred(bird, 1).
body_pred(can, 2).

type(penguin,(bird,)).
type(bird,(bird,)).
type(can,(bird,ability)).

Also, this version of Popper does not support constants in induced rules, so you would need to define these background relations:

can_fly(alice).
can_swim(Betty).

and add can_fly and can_swim to the bias file