The absence of the 
signs in bars 19-20 is to be considered to be rather an inaccuracy of notation – admittedly, Chopin would sometimes omit indications (e.g. pedalling) in fragments that had already appeared with indications, yet the presence of the hairpin in bars 23-24 points to an oversight of the composer. The conclusion is confirmed by the signs added in the proofreading of FE in bars 147-148, based on the same notation of A. The range of the signs in bars 23-24 can also raise certain doubts – particularly the sign in bar 24 is clearly longer than the previous. According to us, it is more likely that Chopin wrote the signs more diligently for the 1st time – see bars 3-8. We also consider that the slightly shorter signs leave more possibilities of interpretation of this motif, whose performance – according to relations of one of the pupils, Wilhelm von Lenz – posed quite a performance challenge: "It was difficult to please Chopin in this Waltz. Only he was able to [correctly] combine the only (!) semiquaver in the third bar with the following crotchet."
Compare the passage in the sources»
category imprint: Interpretations within context; Differences between sources; Editorial revisions
issues: Inaccuracies in FE, Scope of dynamic hairpins
notation: Articulation, Accents, Hairpins