<p>?- A = {a:{b1:1,b2:2,b3:3}},<br />
A = {a:{b2:2|L}},<br />
B = {a:{b4:4|L}}.</p>
<p>% A = {a:{b2:2,b1:1,b3:3}},<br />
% L = {b1:1,b3:3},<br />
% B = {a:{b4:4}}</p>
<p><br />
?- A = {a:{b1:1,b2:2,b3:3}}, A = {a:{b2:2|L}}, B = {a:{b4:4|L}}, display(B),nl, fs_writeAVM(B), display(B),nl. <br />
% {(:(a,{(:(b4,4))}))} % |~ ~| % | a:|~ ~| | % | | b4:4 | | % | | b1:1 | | % | | b3:3 | | % | |_ _| | % |_ _| % {(:(a,{(:(b4,4),(:(b1,1),(:(b3,3))))}))} % <br />
% A = {a:{b2:2,b1:1,b3:3}}, % L = {b1:1,b3:3}, % B = {a:{b4:4,b1:1,b3:3}}</p>