Menu
I wanted to write a Prolog program to find equality of two lists, where the order of elements
doesn't matter. So I wrote the following:
del(_, [], []) .
del(X, [X|T], T).
del(X, [H|T], [H|T1]) :-
X \= H,
del(X, T, T1).
member(X, [X|_]).
member(X, [_|T]) :-
member(X, T).
equal([], []).
equal([X], [X]).
equal([H1|T], L2) :-
member(H1, L2),
del(H1, L2, L3),
equal(T, L3).
But when I give input like equal([1,2,3],X)., it doesn't show all possible values of X. Instead, the program hangs in the middle. What could be the reason?
506
“prolog check if 2 lists have the same items” Code Answercommon_list([X],[X]). common_list([X|Tail],Y):- member(X,Y).
In Prolog list elements are enclosed by brackets and separated by commas. Another way to represent a list is to use the head/tail notation [H|T]. Here the head of the list, H, is separated from the tail of the list, T, by a vertical bar. The tail of a list is the original list with its first element removed.
match([Elem|Tail],Num,Num,Elem). match([Elem|Tail],Num,C,MatchedNumber):- match(Tail,Num,N,Elem), C is N+1. In the first line I say, if the requested element number is equal to counter, then give the first element of the current list to the variable called MatchedNumber .
isSubset([],_).
isSubset([H|T],Y):-
member(H,Y),
select(H,Y,Z),
isSubset(T,Z).
equal(X,Y):-
isSubset(X,Y),
isSubset(Y,X).
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
