<P> In some pieces in sonata form, in the recapitulation, the first subject group is omitted, leaving only the second subject group, like the second movement of Haydn's Sonata Hob . XVI / 35, as well as the opening movements of Chopin's Piano Sonata No. 2 and No. 3 . It is also possible for the first subject group to be slightly different in comparison of the exposition, like the fourth movement of Dvorak's Symphony No. 9 . Another example occurs in the finale of Mozart's string quartet KV 387, where the opening of the first subject group is cut, and in the quintet KV 515, where a later portion of the first subject group is cut . On the other hand, it is also possible for the subject groups to be reversed in order, like the fourth movement of Bruckner's Symphony No. 7, or the first movement of Mozart's piano sonata in D major, KV 311 . It is also possible for the second subject group to be omitted, like the fourth movement of Shostakovich's Symphony No. 5, as well as the second movement of Beethoven's String Quartet No. 9 . The second subject group's melody can be different compared to the exposition, like Haydn's Symphony No. 44 . Such melodic adjustment is common in minor - key sonata forms, when the mode of the second subject needs to be changed, for example in the opening movement of Mozart's wind serenade KV 388 . </P> <P> Occasionally, especially in some Romantic works, the sonata form extends only as far as the end of the exposition, at which point the piece transitions directly into the next movement instead of a development section . One example is Henryk Wieniawski's Violin Concerto No. 2 in D minor . Another example is Fritz Seitz's Violin Concertos for students, where such a truncated sonata form is used ostensibly to cut down on the first movements' length . Sometimes, the third movement of such works is the recapitulation of the first movement (one example being Franz Strauss' Horn Concerto in C Minor), making the entire work effectively a single - movement sonata . </P> <P> Some Classical slow movements involve a different sort of truncation, in which the development section is replaced altogether by a short retransition . This occurs in the slow movements of Mozart's quartets KV 387, KV 458, KV 465, KV 575, and KV 589 . It is also common in overtures, occurring for example in Schubert's Overture in the Italian Style in C, D 590 . This is distinct from a short development, such as in the opening movement of Mozart's Violin Sonata in G major, KV 379 . </P> <P> An important variant on traditional sonata - allegro form is found in the first movement of the Classical concerto . Here, the sonata - allegro's customary' repeated exposition' is replaced by two different but related sections: the' tutti exposition' and the' solo exposition' . Prototypically the' tutti exposition' does not feature the soloist (except, in early classical works, in a' continuo' role), and does not contain the decisive sonata - exposition modulation to the secondary key . Only when the' solo exposition' is under way does the solo instrument assert itself and participate in the move to (classically) the dominant or relative major . The situation is only seemingly different in the case of such late classical works as Beethoven's piano concertos No. 4 and No. 5, where the soloist is heard at the outset: as the later unfolding of those movements makes clear, the opening piano solo or early piano flourishes actually precede the start of the exposition proper . This device is also found in an early Mozart concerto, No. 9, as well as in many Romantic concertos, such as Grieg's A minor concerto or Brahms' B ♭ major concerto . </P>

The two themes of the classic sonata form