question: What piece did Chopin debut after returning to Warsaw ?
answer: Piano Concerto No. 2 in F minor , Op. 21
turker_answer: The ` Piano Concerto No. 2 in F minor , Op. 21 ' is the piece that Chopin debuted after returning to Warsaw .
rule-based: Chopin debut Piano Concerto No. 2 in F minor , Op. 21 after returning to Warsaw .