autocrop
-5 20 setxrange
-10 10 setyrange
setTimes
20 setxunit
#tex# $A_1$ %% label0
#tex# $B_1$ %% label1
#tex# $A_2$ %% label2
#tex# $B_2$ %% label3

/treenodesep 15 def
/levelsep 3.5 def
-3 0 () TRc rootnode
[right
   /label1 TRc (?) ucput 
   [
      /label2 TRc (?) dcput [(?) TRc]
      /label3 TRc (?) ucput [(?) TRc]
   ]
   /label0 TRc (?) ucput
   [
      /label2 TRc (?) dcput [(?) TRc]
      /label3 TRc (?) ucput [(?) TRc]
   ]
] tree*