Prolog Database Question

[g0blu322]

Hi,

So I'm trying to finish up a project for a class. It's a "dating database". It includes 5 males, and 5 females. I have to match them up using the following rules:
(a) Only opposite sex can be matched
(b) Male candidate should have a higher age than Female candidate
(c) Male candidate should have a higher or equivalent education, compared with Female candidate
The following search rules of this database are assumed and should be implemented in your database:
(d) datable search: to find only the opposite-sex candidates who satisfy the aforementioned matching rules
(e) datable_weight search: to find only the opposite-sex candidates who satisfy the aforementioned matching rules and have a less weight than a specified threshold.

Perform the following test cases:

datable(alex, X).
datable(frank, X).
datable_weight(betty,170,X).
datable_weight(sussan,170,X).

In the above cases, 170 refers to the weight threshold.

****Here's my code:*****
%% The database %%

% values meaning person(name,age,sex,height,weight,edu,sa…
person(alex, 20,m,160,150,hs,30).
person(betty, 20,f,158,148,hs,28).
person(charles, 30,m,165,155,bach,35).
person(david, 35,m,170,160,bach,40).
person(edward, 40,m,175,165,master,50)…
person(frank, 45,m,180,180,phd,60).
person(keley, 25,f,163,153,hs,33).
person(victoria,30,f,168,158,bach,38).
person(timbeley,35,f,173,163,master,48…
person(sussan, 40,f,178,168,phd,58).

size_database(N) :- N is 10.

%% end of the database %%


%% list functions %%

append([X|Y],Z,[X|W]) :- append(Y,Z,W).
append([],X,X).

member(X,[L|_]) :- X == L. % swi prolog is dumb...
member(X,[_|R]) :- member(X,R).

cons(X,R,[X|R]).

%% end of list fucntions %%


%% gender functions %%

% m ascii value is 109
% f ascii value is 102

male(Name) :- person(Name,B,Sex,D,E,F,G), atom_char(Sex,Num), Num = 109.
female(Name) :- person(Name,B,Sex,D,E,F,G), atom_char(Sex,Num), Num = 102.

%% end of gender functions %%

% true if the first person has a higher age
higherAge(Name1,Name2) :- person(Name1,B_AGE,C,D,E,F,G),
person(Name2,Y_AGE,X,W,V,U,T), B_AGE > Y_AGE.


%% education functions %%

% assigning values to educations
eduNum(hs,N) :- N is 0.
eduNum(bach,N) :- N is 1.
eduNum(master,N) :- N is 2.
eduNum(phd,N) :- N is 3.

% true if Edu1 is greater or equal to Edu2
greaterEdu(Edu1,Edu2) :- eduNum(Edu1,En1), eduNum(Edu2,En2),
En1 >= En2.

% true if the first person has a higher education
higherEdu(Name1,Name2) :- person(Name1,B,C,D,E,F_EDU,G),
person(Name2,Y,X,W,V,U_EDU,T),greate…

%% end of education functions %%


datable(Name1,Name2) :- male(Name1), female(Name2),
higherEdu(Name1,Name2), higherAge(Name1,Name2).
datable(Name1,Name2) :- female(Name1), male(Name2),
higherEdu(Name2,Name1), higherAge(Name2,Name1).

datable_weight(Name1,Weight,Name2) :- datable(Name1,Name2),
person(Name2,Y,X,W,V_Weight,U,T),
Weight >= V_Weight.

% doesn't work...
datableList(Name,List) :- datableList(Name,List,0).

datableList(Name,List,Index) :- datable(Name,X),
not(member(X,List)), append(List,X,List),
size_database(Size), Index =< Size,
Index is Index + 1,
datableList(Name,List,Index).


When I run it, it always just picks the first opposite-sex member from the list, instead of using the rules. Any suggestions or help?