isdicomplement:=lambda(i)
  and(
    forall(x in L, forall(y in L,
      if <=(indexof(L, y), i) then
        yc:=item(argumentlist,indexof(L,y));
        infxy:=inf(x,y);
        infxyc:=inf(x,yc);
        s:=sup(infxy,infxyc);
        if equal(s,x) then true else false endif
      else true endif)),
    forall(x in L,
      if <=(indexof(L, x), i) then
        xc:=item(argumentlist,indexof(L,x));
        if <=(indexof(L, xc), i) then
          xcc:=item(argumentlist,indexof(L,xc));
          if <=(xcc,x) then true else false endif
        else true endif
      else true endif),
    forall(x in L, forall(y in L,
      if and(<=(indexof(L, x), i),<=(indexof(L, y), i),<=(x,y)) then
        xc:=item(argumentlist,indexof(L,x));
        yc:=item(argumentlist,indexof(L,y));
        if >=(xc,yc) then true else false endif
      else true endif)))
endlambda;

findnextlist:=lambda(i)
  for k in L do 
    setitem(argumentlist, i, k);
    if isdicomplement(i) then
      if equal(i,maxindex) then 
        numfound:=+(numfound,1);
        writeln("");
        write("No. "); writeln(numfound);
        for k1 in L do write(k1); write(" -> "); writeln(item(argumentlist,indexof(L,k1))) endfor;
        true
      else findnextlist(+(i,1)) endif
    else false endif
  endfor
endlambda;

L:=listprompt("Select a structure", structures);
prepare(L);
maxindex:=difference(card(L),1);
argumentlist:=emptyset;
numfound:=0;
for e in L do additem(argumentlist, item(L,0)) endfor;
findnextlist(0);