Expert system using PyDatalog to model and infer various family relations

Question

I'm working on an expert system using PyDatalog to model and infer various family relations.

This is the data used (loaded from a CSV file):

        name father_name mother_name  gender
0      Ahmad      Bachar       Rafah    Male
1      Amjad      Bachar       Rafah    Male
2      Danah      Bachar       Rafah  Female
3      Yazan      Hassan      Ghalia    Male
4       Leen      Hassan      Ghalia  Female
5       Dema       Faiaz       Sahar  Female
6      Dania       Faiaz       Sahar  Female
7      Tareq       Faiaz       Sahar    Male
8      Asmaa      Waleed       Hanan  Female
9       Alaa      Waleed       Hanan  Female
10   Tasneem      Waleed       Hanan  Female
11     Firas      Waleed       Hanan    Male
12    Farouk     Shareef      Sameah    Male
13    Usaema       Saeed      Adebeh  Female
14    Bachar      Farouk      Usaema    Male
15    Hassan      Farouk      Usaema    Male
16     Rafah      Zuhair     Rukaieh  Female
17    Zoukaa      Zuhair     Rukaieh  Female
18    Lujain       Adnan      Zoukaa  Female
19  Mohammad       Adnan      Zoukaa    Male

First I added the terms:

pyDatalog.create_terms('X,Y,Z,W, parent, male, female, father_of, mother_of, 
son, daughter, aunt, uncle, cousin, niece, nephew, sibling, brother, sister')

And this is how I am defining the rules son, male, daughter, female, father_of, mother_of:

for index, row in data.iterrows():
    name, father_name, mother_name, gender = row['name'], row['father_name'], row['mother_name'], row['gender']
    if gender == 'Male':
        +son(name, father_name)
        +son(name, mother_name)
        +male(name)
    else:
        +daughter(name, father_name)
        +daughter(name, mother_name)
        +female(name)


    +father_of(father_name, name)
    +mother_of(mother_name, name)

Testing the rules gave the right answers:

print(son(X, "Bachar"))
print(son(X, "Sahar"))
# Output:
X    
-----
Amjad
Ahmad
X    
-----
Tareq

This is for the parent, brother, sister, sibling also: (Won't include the results to avoid making the question long but tested and worked well 100%)

parent(X, Y) <= father_of(X, Y)
parent(X, Y) <= mother_of(X, Y)
brother(X, Y) <= (parent(Z, X) & parent(Z, Y) & male(X) & (X != Y))
sister(X, Y) <= (parent(Z, X) & parent(Z, Y) & (X != Y) & female(X))
sibling(X,Y) <= parent(Z, X) & parent(Z, Y) & (X != Y)

The issue and purpose of the question is defining the uncle and aunt: I wrote this:

uncle(X, Y) <= brother(X, Z) & parent(Z, Y) & male(X)
aunt(X, Y) <= sister(X, Z) & parent(Z, Y) & female(X)
cousin(X, Y) <= parent(Z, X) & (sister(X, Z) & parent(Z, Y))

Testing it with the "Yazan" and "Ahmad" is OK but with "Asmaa" it outputs an empty list, if you go to the data above the output should be "Bachar, Hassan". The same in the aunt and cousin rules also output wrong answers. Is there something I'm missing here or needs to be corrected?

Answer 1

I went down to the PyDatalog Docs and checked the code written using their interactive tutorial, one issue I found was related to Google Colab itself and I had to terminate the session and start a new one.
Fixing the problem required additional data to be included, so according to PyDatalog an empty list [] is also could be an indcatior to an error in the logic or the Facts and rules declartion which in return would not be resolved or detcted easily.
What I did to solve that? The simple answer is changing the logic how reltives family relationships are definded and adding an information about cousin's parents like i.e. Grandparents and siblings.