As has already been indicated in bar 17, we consider the missing slurs to be Chopin's oversight. The need for and the range of the slur in the 2nd half of bar 19 seem to be obvious (cf. identical figures in bar 16 and 21); they were added already in EE and GE3. In turn, one could imagine the first two quavers in bar 20 being performed with another articulation – see e.g. similar bar 61; however, the slur encompassing the last 6 quavers in bar 20 rather excludes such a varied articulation. The missing pedal mark on the 1st beat in bar 20 may also be considered an argument for performing the bass note legato.
Compare the passage in the sources»
category imprint: Differences between sources; Editorial revisions
issues: EE revisions, GE revisions
notation: Slurs