LARTC - Nov 2005 - is it possible?

Hello. I wonder to know is it possible and how?


	       1:
		|
	       1:1
	      / | \
	     /  |  \
	    /   |   \
  	   /   1:3   \
	  /	      \
         1:2	       \
			\
			1:4
		       /   \
		      /     \
		     /       \
		   a?:b?      \
	          /    \       ?     
                 /      \
                /        \
                ?         ?