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b. 19

composition: Op. 25 No 1, Etude in A♭ major

..

The difference between the abbreviated notations of AI (repetition signs for 2 last figures) and A (signs for all 3 last figures) could suggest that in the latter all four notes are supposed to have normal ("big") note heads. According to us, the notation of A is to be interpreted as a simplified version of the notation of AI, which is also confirmed by FE and EE.
In GE1 (→GE1a), the note on the 2nd beat of the bar is also written as "big", which was corrected in GE2 (→GE3).

category imprint: Interpretations within context; Differences between sources

issues: Authentic corrections of GE , Inaccuracies in A

b. 19-20

composition: Op. 25 No 1, Etude in A♭ major

4 big notes in AI & EE1

8 big notes in A, FE & GE1a (→GE2GE3)

Small notes in CDP & EE2 (→EE3)

5 big notes in GE1

..

In the main text we give the version of A, confirmed by FE and most probably by Chopin proofreading of GE1a (→GE2GE3). The notation of GE1 is erroneous, while AI and EE1 include the original concept of separating the tenor voice only in the part creating a descending melodic line. The versions of CDP and EE2 (→EE3) are certainly non-authentic.

category imprint: Differences between sources; Corrections & alterations

issues: Authentic corrections of GE

b. 21

composition: Op. 25 No 1, Etude in A♭ major

6 notes in AI

5 notes in A (→CDP,GE), FE & EE

..

The quintuplet of the final version ensures a rhythmically smooth return to the sextuplet movement.

category imprint: Differences between sources; Corrections & alterations

b. 26

composition: Op. 25 No 1, Etude in A♭ major

Large noteheads in AI

Big & small notehead in A (→GE1)

Small noteheads in FE, EE & GE2 (→GE3)

..

The deletions of the 1st note on the 2nd and 4th beats of the bar, visible in A, suggest that Chopin hesitated whether to write these notes as big or small. The result of these corrections is not entirely clear (particularly on the 2nd beat); however, it seems to be more plausible that it concerned the transition to small notes, as it is in FE and EE.

category imprint: Corrections & alterations; Source & stylistic information

issues: Chopin's hesitations , Deletions in A

b. 27-28

composition: Op. 25 No 1, Etude in A♭ major

Big noteheads in AI

Small noteheads in A (→CDP,GE), FE & EE

..

In AI, same as in the previous bar, it is also the semiquavers on the 2nd and 4th beats of the bar that are singled out with a big note head. In A it is clearly visible that Chopin renounced such a frequent accentuation of bass notes.

category imprint: Differences between sources; Corrections & alterations