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b. 17

composition: Op. 25 No 4, Etude in A minor

..

In EE1 there is no  before the last quaver in the upper voice in the R.H. This patent inaccuracy in this context – of the engraver or the person performing the base text – was corrected in EE2 (→EE3).

category imprint: Interpretations within context; Differences between sources

issues: EE revisions , Errors in EE

b. 18

composition: Op. 25 No 4, Etude in A minor

 below L.H. in A (→FC,FE) & EE

 between staves in GE

..

Moving the  hairpins in GE between the staves is certainly an arbitrary decision of the engraver, in this case, it is not entirely indifferent for the meaning of this sign.

category imprint: Differences between sources

issues: Scope of dynamic hairpins , GE revisions

b. 19-22

composition: Op. 25 No 4, Etude in A minor

Different accents in A

Short accents in FC (→GE) & FE

Vertical accents in EE

..

The varied accents – long over crotchets and short over quavers – are written in A. However, it must be stated that the difference is not obvious at first glance and was not reproduced in any of the remaining sources.
The use of vertical accents is certainly an arbitrary decision of the engraver of EE (cf., e.g., the Etude in F major, No. 3, bars 29-31).

category imprint: Graphic ambiguousness; Differences between sources

issues: Long accents

b. 20

composition: Op. 25 No 4, Etude in A minor

..

GE2 (→GE3) added cautionary naturals before a1 and a in the last quaver. Similarly in bar 22.

category imprint: Differences between sources

issues: GE revisions

b. 21

composition: Op. 25 No 4, Etude in A minor

No slur in A & #EE

Slur in FC (→GE) & FE

..

The slur in FC was almost certainly added by Chopin, who added an analogous slur while proofreading FE.

category imprint: Differences between sources

issues: Authentic corrections of FE , Authentic corrections of FC