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b. 17-18

composition: Op. 50 No. 1, Mazurka in G major

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There is a visible correction in A1: deletion of the double bar line before b. 17. According to us, the change was introduced by Chopin in an already finished manuscript, perhaps at the time of writing [A2]; anyway, after the slurs had been written. 

category imprint: Corrections & alterations; Source & stylistic information

issues: Corrections in A , Deletions in A

b. 18

composition: Op. 50 No. 1, Mazurka in G major

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We add a cautionary  before a1 in the main text.

category imprint: Editorial revisions

b. 21

composition: Op. 50 No. 1, Mazurka in G major

Staccato quaver & semiquaver in A1

Quaver & semiquaver in FE (→EE)

2 quavers in GE

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There are no reasons to consider the version of GE to be erroneous: the change of rhythm with respect to the remaining sources is confirmed by the complementary slur. On the other hand, deprived of insight into [A2], one cannot state whether Chopin replaced therein a previous version or whether he simply wrote another one, which does not give us grounds to consider the previous one to be rejected. Due to the above reason, we consider both possibilities equal.
The missing staccato dot in FE (→EE) is most probably an oversight. 

category imprint: Differences between sources; Corrections & alterations

issues: Dotted or even rhythm

b. 21-22

composition: Op. 50 No. 1, Mazurka in G major

Slur from f1 in A1

Slur from e1 in FE (→EE) & GE

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According to us, there is no reason to interpret the beginning of the slur of A1 differently than in an analogous phrase four bars earlier. In spite of that, in FE (→EE) the beginning of the slur was placed already over the e1 minim. It implies that the same slur in GE may also be inaccurate, hence we consider both possibilities equal. However, in the main text we preserve the text of the principal source, since in [A2] Chopin, having changed the articulation of the initial motif of this phrase, could have led the next slur slightly differently too.

category imprint: Graphic ambiguousness; Differences between sources

issues: Inaccurate slurs in A

b. 21-22

composition: Op. 50 No. 1, Mazurka in G major

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There is no tie of g in A1, which must be Chopin's oversight: cf. b. 17-18. The tie was added in FE (→EE), which, however, does not need to point to Chopin's proofreading, since such additions would be routinely introduced by the publishers, sometimes explicitly contrary to Chopin's intention, e.g. in the Mazurka in D Major, Op. 33 No. 3, b. 8-9 and analog. or in the Scherzo in C Minor, Op. 39, b. 34-35.  

category imprint: Differences between sources

issues: Errors of A , FE revisions