Question: What nationality was the composer who wrote 'The First Piano Sonata in 1946'?
Sentence (from "Piano sonatas (Boulez)"): The First Piano Sonata in 1946, a Second Piano Sonata in 1948, and a Third Piano Sonata was composed in 1955–57 with further elaborations up to at least 1963, though only two of its movements (and a fragment of another) have been published.
Relevant evidence: Yes