Iterative deepening over a descending variable

[razetime]

I have the following predicate, which returns subsequences:

sl([], []).
sl([X|A], [X|B]) :-
    sl(A, B).
sl([_|A], B) :-
    sl(A, B).

I want to perform an iterative deepening search of lists L that satisfy sl([1,2,3],L), but I want to start the search from the maximum possible length.

I attempted the following. Regardless of how i setup the range for length, the interpreter seems to always begin at 0.

Ls in -3..0,L #= -Ls,length(X,L),sl([1,2,3],X).

I'm wondering how I should patch sl/2 or my query to get the result I want, which should be something like:

X=[1,2,3];
X=[1,2];
X=[1,3];
X=[2,3];
...

[razetime]

indomain/1 seems to work here, but it doesn't seem to be the most elegant solution to this problem.

Ls in -3..0,indomain(Ls),L#=-Ls,length(X,L),sl([1,2,3],X).

[UWN]

?- N in 0..3, labeling([down], [N]),length(Xs, N).
   N = 3, Xs = [_A,_B,_C]
;  N = 2, Xs = [_A,_B]
;  N = 1, Xs = [_A]
;  N = 0, Xs = [].
?- N in 0..3, labeling([down], [N]),length(Xs, N), sl([1,2,3],Xs).
   N = 3, Xs = [1,2,3]
;  N = 2, Xs = [1,2]
;  N = 2, Xs = [1,3]
;  N = 2, Xs = [2,3]
;  N = 1, Xs = [1]
;  N = 1, Xs = [2]
;  N = 1, Xs = [3]
;  N = 0, Xs = [].