Hi Joseph, thanks for your explanations. You are right. Seems it was too late in the night for me :-) In the meantime I found the following in the specs:
------------------------- For deletion components, the old values in the annotations update match the annotations of each item in the input document processed by the component, and the new values match the annotations of the rightmost item generated so far. All annotation keys that have different values in the processed item and the rightmost item generated so far are present in the annotations update. If no items have been generated so far, the new values are null, and all annotation keys of the deleted items must be present in the annotations update. --------------- My random mutation generator did produce false mutations and the verifier did not check for the correctness of the annotations around a delete. Will fix this. Greetings Torben 2010/8/6 Joseph Gentle <[email protected]> > In this case, the delete op must also delete the annotation. If it didn't, > the op wouldn't be invertable (if you apply the op then apply its inverse, > you'll end up removing the annotation). > > Your example should look like: > mutation1 := anno('bold': 'true' -> NULL), delete 'ab', anno(end 'bold'), > retain 2 > mutation2 := retain 2, insert 'x', retain 2 > > After transform, mutation1_t is the same as you suggested, but > > mutation2_t := anno ('bold': NULL -> true) insert 'x', anno (end 'bold'), > retain 2 > > ... and you get the correct behaviour. > > -J > > > On Fri, Aug 6, 2010 at 11:14 AM, Torben Weis <[email protected]>wrote: > >> Hi, >> >> I encountered a problem while unit testing my OT code. Either I just found >> a major flaw in the OT algorithm (i.e. a flaw that is almost impossible to >> repair) or I am too tired to see the solution. Here is the problem: >> >> Let "A, B ,C" be BOLD letters, and "a, b, c" denote the same letters, but >> not in bold. >> Now imagine a simple document with the content >> >> doc := ABcd >> >> i.e. "ab" in bold and "cd" not in bold. Now two users edit the document >> concurrently. >> >> mutation1 := delete:2, retain:2 >> mutation2 := retain:2, insert:"x", retain:2 >> >> i.e. user1 sees "cd" and user2 sees "ABXcd". Notice that the "x" is bold >> -> "X", because in word processors you inherit the style from the left. This >> is important here! >> >> Now I transform both mutations and I get: >> >> mutation1_t := delete:2 retain:3 // I skip the inserted "x" -> >> therefore retain2 >> mutation2_t := insert"x", retain:2 // No need to skip "AB", because >> they are already deleted >> >> Now user1 one applies mutation2_t and user2 applies mutation1_t. They >> should end up in the same state. >> >> However, in the end user1 sees "xcd" and user2 sees "Xcd". The difference >> is that x is not consistently annotated. >> >> As far as can see right now, the transformation function cannot do >> anything because it needs style annotation that is only in the document but >> not in the mutations. >> >> I hope that someone can enlighten me here, because otherwise the OT >> algorithm is broken. >> >> Greetings >> Torben >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Wave Protocol" group. >> To post to this group, send email to [email protected]. >> To unsubscribe from this group, send email to >> [email protected]<wave-protocol%[email protected]> >> . >> For more options, visit this group at >> http://groups.google.com/group/wave-protocol?hl=en. >> > > -- > You received this message because you are subscribed to the Google Groups > "Wave Protocol" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]<wave-protocol%[email protected]> > . > For more options, visit this group at > http://groups.google.com/group/wave-protocol?hl=en. > -- --------------------------- Prof. Torben Weis Universitaet Duisburg-Essen [email protected] -- You received this message because you are subscribed to the Google Groups "Wave Protocol" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/wave-protocol?hl=en.
