'''Piano Sonata No. 1 in C minor, Op. 4''' was written by Frédéric Chopin in 1828 (probably begun around July).According to [http://www.chopin.pl/edycja_1999_2009/kronika/kronika2_en.html the Chopin chronicle site]. It was written during Chopin's time as a student with Józef Elsner, to whom the sonata is dedicated. Despite having a low opus number, the sonata was not published until 1851, two years after Chopin's death, by Tobias Haslinger in Vienna. This sonata has been highly underestimated, in terms both of musical difficulty and quality. Later editions, like Breitkopf & Härtel (1880), and Augener (1882), explicitly label it as "nachlass" or posthumous.