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b. 7

composition: Op. 10 No 6, Etude in E♭ minor

f in A

in FE (→GE,EE)

..

In A there is no  returning f on the 9th semiquaver of the bar. It is almost certainly an oversight, corrected by Chopin in a proofreading of FE (→GE,EE).

category imprint: Differences between sources

issues: Omissions to cancel alteration , Authentic corrections of FE

b. 8

composition: Op. 10 No 6, Etude in E♭ minor

..

In A there is no  returning don the penultimate semiquaver in the R.H. The natural next to the subsequent note proves that Chopin forgot about the existence of d1 at the beginning of the bar. The sign was added in a proofreading of FE (→GE,EE).

category imprint: Interpretations within context; Differences between sources

issues: Omissions to cancel alteration , Errors of A , Authentic corrections of FE

b. 12

composition: Op. 10 No 6, Etude in E♭ minor

..

In this context the missing  before d must be considered as Chopin's oversight (in the remaining two analogous bars the sign is both in A and the remaining sources).

category imprint: Differences between sources

issues: EE revisions , GE revisions , Cautionary accidentals

b. 15

composition: Op. 10 No 6, Etude in E♭ minor

f1 & f in A

f1 & f in FE

GE & EE

..

The version of A may be the inadvertently left original edition of this bar (or maybe even of bar 7). In any case, a proofreading of FE – despite a possible error in the 2nd half of the bar – does not leave any doubts concerning the final intention of the composer. The natural returning f, which in FE is only before the penultimate note of the bar, was moved before the 7th semiquaver in GE and EE, which may render Chopin's intention accurately. 

category imprint: Differences between sources

issues: EE revisions , Errors in FE , GE revisions , Errors of A , Authentic corrections of FE

b. 15

composition: Op. 10 No 6, Etude in E♭ minor

..

The  returning g, without a doubt omitted in A by mistake, was added in a proofreading of FE (→GE,EE).

category imprint: Differences between sources

issues: Omissions to cancel alteration , Errors of A , Authentic corrections of FE