findall instead of bagof can also help for these cases. | ?- findall(A, (tree(A, N), branch(N)), As). As = [n,n1] yes See https://lpn.swi-prolog

findall instead of bagof can also help for these cases. | ?- findall(A, (tree(A, N), branch(N)), As). As = [n,n1] yes See https://lpn.swi-prolog.org/lpnpage.php?pagetype=html&pageid=lpn-htmlse49 https://lpn.swi-prolog.org/lpnpage.php?pagetype=html&pageid=...