Piano Sonata in A-flat major, D 557 (Schubert)

Franz Schubert's Piano Sonata in A-flat major 557 was composed in May 1817.
Movements.
The work is relatively short and a performance takes somewhat between 10 and 15 minutes. The sonata is cheerful and uncomplicated, and carries remembrances of Mozart and the Baroque era.
The fact that the last movement is in the key of E-flat major rather than the tonic key of A-flat major is evidence in favor of Schubert possibly intending to add a fourth movement, although the extant third movement has much of the character of a finale. At the time this was written it was quite unusual to end a composition in another key than its tonic, however Schubert did do this in some of his early works, e.g. ("Auf der Donau", beginning in E-flat major and ending in F-sharp minor).
Score.
The sonata was first published in 1888, in the Breitkopf & Härtel complete edition.
The autograph of the sonata, dated May 1817, is incomplete — it stops at the 28th measure of the third movement, but there is a contemporary complete manuscript.
D. 557 was first published in 1888 as No. 3 of the Piano Sonatas volume (Series X) of the "Kritisch durchgesehene Gesammtausgabe".
Both Paul Badura-Skoda (Henle) and Martino Tirimo (Wiener Urtext) published an Urtext edition in 1997.
In the New Schubert Edition D. 557 is given in VII/2/1.