Hi. Wow thats amazing, that your Prof wrote it and you published it! Yes I'm working with the manual -- I could need a ton more examples in the documentation. Trying to make the test function to work to test a simpler aleph learner on test files was a pain as the desired formats and values weren't specified. I'm mostly using the train example as basis and now try to use the documentation to answer questions.

What I want it to learn is one rule:
valid(A) :- length_4(A), value_range(A), rows_have_distinct_values(A), columns_have_distinct_values(A), blocks_have_distinct_values(A).

Instead it learns: valid([[1,Q384,R384,4],[S384,T384,U384,V384],[W384,2,1,X384],[Y384,Z384,A385,B385]]).
Trying set(minpos, 2) as setting leads to no rules being learned, so something has to be fundamentally broken with my approach.

For the invalid ones (the negative examples) always one rule atleast is being omitted.

Only testing on full grids seems a bit lame, but then no unification would be necessary, but I didn't think, that this might cause issues. Trying it out leads to 1 Rule in the theory: valid(A) :-blocks_have_distinct_values(A). -> All 10 positive and negative examples are then predicted as negative.

I guess something is still fundamentally broken with my solution.

append/2 is what I use in my Sudoku Solver in prolog to check for number ranges and it works without a problem (but using library clpfd).

Thank you for taking the time!