kowey/gist:9804330

## gistfile1.md

      
    Raw
  

              gistfile1.md
            
          
    Starting dependency tree

     e2
attr / \ purpose
    /   \
   e1   e4
        /\
  attr /  \ comment
      e3  e5

Ambiguities:

e4 -> e3 or e4 -> e5 first
e2 -> e1 or e2 -> e4 first?

Scenario A (e3, e4)


First e4 -attr-> e3
    e2
   /  \
  e1  +----------+
      |   attr   |
      | S /  \ N |
      | e3   e4  |
      +----------+
          \
          e5


Then e4 -comment-> e5
   e2
  /  \
 e1  +-------------+
     |    comment  |
     |   N /   \ S |
     |    /     \  |
     | e3..e4   e5 |
     +-------------+


Then e2 -purpose-> e4
     +--------------+
     |    purpose   |
     |  N /   \ S   |
     |   /     \    |
   / |  e2   e3..e5 |
  e1 +--------------+


Finally, e2 -attr-> e1
     +--------------+
     |    attr      |
     |  S /   \ N   |
     |   /     \    |
     |  e1   e2..e5 |
     +--------------+


So far so good, but were we just lucky?
Scenario B (e3, e1)


Backing up to the result of step 2 above
    e2
   / \
  /   \
 e1  +------+
     |e3..e5|
     +------+


Now this time, we swing left first (e2 -attr-> e1):
 +--------------+
 |    attr      |
 |  S  /\ N     |
 |    /  \      |
 |  e1    e2    |
 +--------------+
          \
           \
          +------+
          |e3..e5|
          +------+


And then do the e2 - purpose -> e4 link
 +----------------+
 |    purpose     |
 |   N  /\ S      |
 |     /  \       |
 |    /    \      |
 |  e1..e2 e3..e5 |
 +----------------+


So that worked out reasonably well too. Maybe we're OK so long as we
don't have crossing dependencies. I seem to remember that I could blow
up the converter just by changing the order I processed the nodes in
these ambiguous cases though; will have to revisit next week
(maybe when there are 3 links, there's a way you can process them such that you create a crossing dependency and thereby be stuck in terms of how to build the RST tree, maybe I misremember)