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b. 26

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

..

The cautionary  before d2 at the end of bar 26 is in all sources. A respective sign in the L.H. was added only in GE and EE2 (→EE3). 

category imprint: Differences between sources; Editorial revisions

issues: EE revisions , GE revisions , Cautionary accidentals

b. 27

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

​Third a-c1 in A (→FE)

Fifth f-c1 in FC (→GE) & EE

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Both source versions of the last quaver in the L.H. are a result of corrections, certainly (A) or most probably (FC) authentic. Out of these two practically equal versions, to the main text we choose the a-c1 third written in A (→FE). According to our evaluation, the corrections in the L.H. visible in A also in the next two bars prove a thought-out decision of the composer, including all sound aspects of the accompaniment in this fragment. 

category imprint: Differences between sources; Corrections & alterations

issues: Deletions in A , Accompaniment changes

b. 27

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

..

GE2 (→GE3) added cautionary naturals before g2g1 and g on the 4th quaver in the bar.

category imprint: Differences between sources

issues: GE revisions

b. 31

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

..

The last dyad in the bottom voice seems to be a third in A, as the bottom note is written slightly too low. The visible in FE traces of correction prove that it actually misled the engraver and it must have been corrected in print.

category imprint: Source & stylistic information

issues: Inaccurate note pitch in A , Authentic corrections of FE

b. 31

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

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In A (→FE) there are no flats before the bottom note of the 2nd quaver in the L.H. and top note of the 3rd chord in the R.H. The sign in the R.H. was added in FC (by the copyist or Chopin). GE and EE include the correct notation.

category imprint: Interpretations within context; Differences between sources

issues: EE revisions , Accidentals in different octaves , GE revisions , Inaccuracies in A