The 
sign, visible in GC, yet absent in the remaining sources, could have been added by Chopin as one of the elements varying the return of this theme (the other ones are the F
1 grace note in bar 50 and, above all, the chromatic scale in bar 52). However, its absence in GE is puzzling, as it seems to be highly unlikely for it to be unnoticed by both the engraver of GE1 and editors preparing GE2. According to us, the sign was considered to be a deletion of the end of the extended (combined) slur. A few such deletions are indeed in GC – in bars 20, 26, 38, 39, 56 and 65 – however, all of them are clearly longer (shorter fragments, e.g., in bars 6-7 remained non-deleted). Taking into account the missing sign in FE and EE and possible doubts concerning its content, in the main text we suggest a mordent in a variant form, in brackets.
Compare the passage in the sources»
category imprint: Graphic ambiguousness; Differences between sources; Corrections & alterations
issues: Main-line changes, Authentic corrections in GC
notation: Ornaments