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The "SymmetricMerge" page has been changed by JulianFoad:
http://wiki.apache.org/subversion/SymmetricMerge?action=diff&rev1=52&rev2=53

Comment:
Illustrate the criss-cross merge.

  Next,  we need to account for cherry-picks.  If there are cherry-picks from  
the source [...], we look for the end of the first gap.  [TODO...]
  
  == Symmetric Merge with Criss-Cross Merge ==
- [danielsh] How does the algorithm cope with the following history: O - common 
parent; A1 - text change; B1 - text change; A2 - merge of B1 to A; B2 - merge 
of A1 to B; and being asked to merge A into (a working copy of) B?
+ The following kind of merge history is known as a 'criss-cross' merge.
  
- [TODO] Graph
+ {{attachment:merge-criss-cross-1.png|criss-cross merge}}
+ 
+ The scenario is notorious for being an awkward case for typical DAG-oriented 
merge algorithms to handle.  There are two possible bases, and neither of them 
is clearly the right one to use, and the choice may make a difference to the 
result in the general case.
+ 
+ This is how Subversion will handle the simple criss-cross merge illustrated 
in the graph.
  
  First we pick a base according to whatever rule we decided.  It could be A1 
or B1.
  

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