Prolog - Tell if abs value of max is greater then abs value of min in list of integers

Question

My task was changed a little. And I need to implement abs and max also in prolog. I need to take list of integer and tell if abs value of max is greater then abs value of min. – M

My code is like this :

ismaxgreater([X],X).
ismaxgreater([X],X):-
    maxlist([X],X).
    %minlist([X],Y),
    %abs([Y],Z),
    %com(X,Z).

maxlist([X],X).
maxlist([X,Y |Rest],Max) :-
    maxlist([Y | Rest], MaxRest),
    max(X,MaxRest,Max).

minlist([X],X).
minlist([X,Y |Rest],Min) :-
    maxlist([Y | Rest], MinRest),
    max(X,MinRest,Min).

com(Max,Min) :- Max>Min,
    write('Max is Bigger Value');
    Max<Min,
    write('Min is Bigger Value').

max(X,Y,X) :- X>= Y.
max(X,Y,Y) :- X < Y.
min(X,Y,X) :- X =< Y.
min(X,Y,Y) :- X > Y.
abs(X,Y) :- X < 0 ->  Y is -X; Y = X.

But I want to enter on Input only like this :

ismaxgreater([1,2,-5,9])

where output should be like :

Max is greater true

Answer 1

In this solution, we find the max and min values and compare Max with the absolute value of Min.

max([X], X) :- !, true.
max([X|List], M):- max(List, M), M >= X.
max([X|List], X):- max(List, M), X > M.

min([X], X) :- !, true.
min([X|List], M):- min(List, M), M <= X.
min([X|List], X):- min(List, M), X > M.

ismaxgreater(X) :- max(X, Max), min(X, Min), Max > abs(Min);