A PrologError raise in function success_set when using build-in predicates

Question

A PrologError raise in function success_set when using build-in predicates

yangdinglou opened this issue 3 years ago · 2 comments

Hello. I tried using the system to learn some properties (expressed by predicates), and the python program returned some error messages. For simplicity, I attempted to locate the problem, and found the issue was accompanied with the use of build-in predicates.

Example1 (with error)

%% The expected predicate is 
%% f(Num, Lst) :- succ(A, Num), last(Lst, A).

%% bias.pl as follows
max_vars(3).
max_body(3).
max_clauses(2).

head_pred(f,2).
body_pred(last,2).
body_pred(succ,2).

%% no content needed in bk.pl, exs.pl as follows
pos(f(3,[4,3,1,2])).
pos(f(3,[4,3,2])).
pos(f(5,[3,4])).

neg(f(1,[4,1,2])).
neg(f(1,[4,3,5,2])).
neg(f(2,[4,3,2])).
neg(f(5,[4,3,2,7])).
neg(f(2,[3,4,5])).

returns the following messages.

Traceback (most recent call last):
  File "popper.py", line 11, in <module>
    _prog, stats = learn_solution(settings)
  File "/home/ydl/Popper/popper/loop.py", line 181, in learn_solution
    timeout(popper, (settings, stats), timeout_duration=int(settings.timeout))
  File "/home/ydl/Popper/popper/util.py", line 47, in timeout
    result = func(*args, **kwargs)
  File "/home/ydl/Popper/popper/loop.py", line 142, in popper
    conf_matrix = tester.test(program)
  File "/home/ydl/Popper/popper/tester.py", line 90, in test
    covered.update(self.success_set([rule]))
  File "/home/ydl/Popper/popper/tester.py", line 83, in success_set
    self.seen_prog[prog_hash] = set(next(self.prolog.query('success_set(Xs)'))['Xs'])
  File "/home/ydl/.local/lib/python3.8/site-packages/pyswip/prolog.py", line 126, in __call__
    raise PrologError("".join(["Caused by: '", query, "'. ",
pyswip.prolog.PrologError: Caused by: 'success_set(Xs)'. Returned: 'error(type_error(integer, [4, 3, 1, 2]), context(:(system, /(succ, 2)), _1654))'.

Example2 (worked)

Based on Example1, by replaceing body_pred(succ,2). with body_pred(my_succ,2). and adding

my_succ(1,2).
my_succ(2,3).
my_succ(3,4).
my_succ(4,5).
my_succ(5,6).

in the background file, the correct predicate f(A,B):-my_succ(C,A),last(B,C). was learned.

Example3 (with error)

Then based on Example2, I tried replacing the predicate last with min_list. One modify is needed in the example file.

%% The expected predicate is 
%% f(Num, Lst) :- my_succ (A, Num), min_list(Lst, A).
%% bias.pl as follows
max_vars(3).
max_body(3).
max_clauses(2).

head_pred(f,2).
body_pred(min_list,2).
body_pred(my_succ,2).
%% exs.pl as follows
pos(f(2,[4,3,1,2])).
pos(f(3,[4,3,2])).
pos(f(4,[3,4])).

neg(f(1,[4,1,2])).
neg(f(1,[4,3,5,2])).
neg(f(2,[4,3,2])).
neg(f(5,[4,3,2,7])).
neg(f(2,[3,4,5])).

then returns the following messages.

Traceback (most recent call last):
  File "popper.py", line 11, in <module>
    _prog, stats = learn_solution(settings)
  File "/home/ydl/Popper/popper/loop.py", line 181, in learn_solution
    timeout(popper, (settings, stats), timeout_duration=int(settings.timeout))
  File "/home/ydl/Popper/popper/util.py", line 47, in timeout
    result = func(*args, **kwargs)
  File "/home/ydl/Popper/popper/loop.py", line 142, in popper
    conf_matrix = tester.test(program)
  File "/home/ydl/Popper/popper/tester.py", line 90, in test
    covered.update(self.success_set([rule]))
  File "/home/ydl/Popper/popper/tester.py", line 83, in success_set
    self.seen_prog[prog_hash] = set(next(self.prolog.query('success_set(Xs)'))['Xs'])
  File "/home/ydl/.local/lib/python3.8/site-packages/pyswip/prolog.py", line 126, in __call__
    raise PrologError("".join(["Caused by: '", query, "'. ",
pyswip.prolog.PrologError: Caused by: 'success_set(Xs)'. Returned: 'error(existence_error(matching_rule, :(lists, min_list(3, [4, 3, 2]))), context(:(lists, /(min_list, 2)), _1026))'.

The environment is SWI-Prolog version 8.4.1 for x86_64-linux (on WSL). I am not sure it is a bug or due to violation of some constraints of the system.

Thanks. (Edited a typo)

Answer 1 · 2022-02-04T13:39:28.000Z

Hi, # Example 1 The problem is SWI-Prolog not failing gracefully because of a type mismatch (when given a list, succ it throws an exception). A quick fix is to add types to the bias file: type(f,(num, list)). type(last,(list, num)). type(succ,(num, num)). The example runs correctly. # Example 3 Similar issue here. min_list is failing ungracefully because of a type mismatch. In addition, SWI-Prolog requires that the first argument of min_list is ground. Therefore, I suggest adding an auxiliary relation to the BK that ensures the first argument is ground: my_min_list(List,Min):- ground(List), min_list(List,Min). I hope that helps

…

On 4 Feb 2022, at 13:11, yangdinglou ***@***.***> wrote: Hello. I tried using the system to learn some properties (expressed by predicates), and the python program returned some error messages. For simplicity, I attempted to locate the problem, and found the issue was accompanied with the use of build-in predicates. Example1 (with error) %% The expected predicate is %% f(Num, Lst) :- succ(A, Num), last(Lst, A). %% bias.pl as follows max_vars(3). max_body(3). max_clauses(2). head_pred(f,2). body_pred(last,2). body_pred(succ,2). %% no content needed in bk.pl, exs.pl as follows pos(f(3,[4,3,1,2])). pos(f(3,[4,3,2])). pos(f(5,[3,4])). neg(f(1,[4,1,2])). neg(f(1,[4,3,5,2])). neg(f(2,[4,3,2])). neg(f(5,[4,3,2,7])). neg(f(2,[3,4,5])). returns the following messages. Traceback (most recent call last): File "popper.py", line 11, in <module> _prog, stats = learn_solution(settings) File "/home/ydl/Popper/popper/loop.py", line 181, in learn_solution timeout(popper, (settings, stats), timeout_duration=int(settings.timeout)) File "/home/ydl/Popper/popper/util.py", line 47, in timeout result = func(*args, **kwargs) File "/home/ydl/Popper/popper/loop.py", line 142, in popper conf_matrix = tester.test(program) File "/home/ydl/Popper/popper/tester.py", line 90, in test covered.update(self.success_set([rule])) File "/home/ydl/Popper/popper/tester.py", line 83, in success_set self.seen_prog[prog_hash] = set(next(self.prolog.query('success_set(Xs)'))['Xs']) File "/home/ydl/.local/lib/python3.8/site-packages/pyswip/prolog.py", line 126, in __call__ raise PrologError("".join(["Caused by: '", query, "'. ", pyswip.prolog.PrologError: Caused by: 'success_set(Xs)'. Returned: 'error(type_error(integer, [4, 3, 1, 2]), context(:(system, /(succ, 2)), _1654))'. Example2 (worked) Based on Example1, by replaceing body_pred(succ,2). with body_pred(my_succ,2). and adding my_succ(1,2). my_succ(2,3). my_succ(3,4). my_succ(4,5). my_succ(5,6). in the background file, the correct predicate f(A,B):-my_succ(C,A),last(B,C). was learned. Example3 (with error) Then based on Example2, I tried replacing the predicate last with min_list. One modify is needed in the example file. %% The expected predicate is %% f(Num, Lst) :- my_succ (A, Num), min_list(Lst, A). %% bias.pl as follows max_vars(3). max_body(3). max_clauses(2). head_pred(f,2). body_pred(min_list,2). body_pred(my_succ,2). %% exs.pl as follows pos(f(2,[4,3,1,2])). pos(f(3,[4,3,2])). pos(f(5,[3,4])). neg(f(1,[4,1,2])). neg(f(1,[4,3,5,2])). neg(f(2,[4,3,2])). neg(f(5,[4,3,2,7])). neg(f(2,[3,4,5])). then returns the following messages. Traceback (most recent call last): File "popper.py", line 11, in <module> _prog, stats = learn_solution(settings) File "/home/ydl/Popper/popper/loop.py", line 181, in learn_solution timeout(popper, (settings, stats), timeout_duration=int(settings.timeout)) File "/home/ydl/Popper/popper/util.py", line 47, in timeout result = func(*args, **kwargs) File "/home/ydl/Popper/popper/loop.py", line 142, in popper conf_matrix = tester.test(program) File "/home/ydl/Popper/popper/tester.py", line 90, in test covered.update(self.success_set([rule])) File "/home/ydl/Popper/popper/tester.py", line 83, in success_set self.seen_prog[prog_hash] = set(next(self.prolog.query('success_set(Xs)'))['Xs']) File "/home/ydl/.local/lib/python3.8/site-packages/pyswip/prolog.py", line 126, in __call__ raise PrologError("".join(["Caused by: '", query, "'. ", pyswip.prolog.PrologError: Caused by: 'success_set(Xs)'. Returned: 'error(existence_error(matching_rule, :(lists, min_list(3, [4, 3, 2]))), context(:(lists, /(min_list, 2)), _1026))'. The environment is SWI-Prolog version 8.4.1 for x86_64-linux (on WSL). I am not sure it is a bug or due to violation of some constraints of the system. Thanks. — Reply to this email directly, view it on GitHub, or unsubscribe. Triage notifications on the go with GitHub Mobile for iOS or Android. You are receiving this because you are subscribed to this thread.

Answer 2 · 2022-02-05T11:59:16.000Z

Thanks Andrew! I get it now.